Best Practices in Developing Proprietary Names for Human Prescription Drug Products; Guidance for Industry: Guidance for Industry

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Best Practices in Developing
Proprietary Names for Human
Prescription Drug Products
Guidance for Industry
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
Center for Biologics Evaluation and Research (CBER)
December 2020
Drug Safety

Best Practices in Developing
Proprietary Names for Human
Prescription Drug Products
Guidance for Industry
Additional copies are available from:
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Food and Drug Administration
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guidances
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research
Center for Biologics Evaluation and Research
December 2020
Drug Safety

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Table of Contents
I. 	INTRODUCTION............................................................................................................. 1
II. 	BACKGROUND ............................................................................................................... 2
III. 	PRESCREENING PROPOSED PROPRIETARY NAME FOR ATTRIBUTES
THAT ARE LIKELY TO CONTRIBUTE TO MEDICATION ERRORS ................ 4
A. 	Obvious Similarities in Spelling and Pronunciation of Proprietary Names ................ 5
B. 	Inert or Inactive Ingredients ............................................................................................ 5
C. 	Combinations of Active Ingredients ................................................................................ 5
D. 	USAN Stems ...................................................................................................................... 5
E. 	Brand Name Extensions ................................................................................................... 6
F. 	Reuse of Proprietary Names ............................................................................................ 7
G. 	Use of Letters and Numbers That Are Unpronounceable as a Word in Proprietary
Names ................................................................................................................................. 8
IV. 	ADDITIONAL BEST PRACTICES FOR EVALUATION OF PROPOSED
PROPRIETARY NAME .................................................................................................. 8
A. 	Names That Include Reference to Product-Specific Attributes ................................... 8
B. 	Medical Abbreviations...................................................................................................... 9
C. 	Modifiers as Components of a Proprietary Name ......................................................... 9
D. 	Dual Proprietary Names................................................................................................. 14
E. 	Proprietary Names of Drug Products Marketed Outside the United States ............. 15
F. 	Incorporation of the Sponsor’s Name ........................................................................... 15
V. 	FURTHER BEST PRACTICES FOR REVIEW, INCLUDING FOR
MISBRANDING AND OTHER LEGAL CONCERNS.............................................. 15
VI. 	RECCOMENDED METHODS FOR EVALUATING RISKS OF MEDICATION
ERROR POSED BY SIMILARITY OF A PROPOSED PROPRIETARY NAME
TO OTHER NAMES ...................................................................................................... 17
A. 	Name Simulation Studies ............................................................................................... 17
B. 	Obtain Medication Error Data for Names That Are Already Marketed .................. 18
C. 	Computational Method To Identify Names With Potential Orthographic, Spelling,
and Phonetic Similarities ................................................................................................ 18
D. 	Safety Determination of Names With Potential Orthographic, Spelling, and
Phonetic Similarities ....................................................................................................... 20
GLOSSARY................................................................................................................................. 22

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DATABASES AND OTHER RESOURCES ............................................................................ 25
APPENDIX A: EXAMPLES OF PREVIOUSLY USED MODIFIERS AND THEIR
COMMONLY UNDERSTOOD MEANINGS ............................................................. 28
APPENDIX B: RESEARCH METHODOLOGY FOR CONDUCTING ............................ 33
MISBRANDING REVIEW............................................................................................ 33
APPENDIX C: RESEARCH METHODOLOGY CONSIDERATIONS FOR
CONDUCTING NAME SIMULATION STUDIES .................................................... 37
APPENDIX D: HIGHLY SIMILAR NAME PAIR CHECKLIST ....................................... 36
APPENDIX E: MODERATELY SIMILAR NAME PAIR CHECKLIST .......................... 40
APPENDIX F: LOW SIMILARITY NAME PAIRS ............................................................. 42

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Guidance for Industry1
Best Practices in Developing Proprietary Names for Human
Prescription Drug Products
This guidance represents the current thinking of the Food and Drug Administration (FDA or Agency) on
this topic. It does not establish any rights for any person and is not binding on FDA or the public. You
can use an alternative approach if it satisfies the requirements of the applicable statutes and regulations.
To discuss an alternative approach, contact the FDA office responsible for this guidance as listed on the
title page.
I. 	INTRODUCTION
FDA is issuing this guidance to help sponsors of human prescription drug products2 develop
proprietary names3 for those products. This guidance describes best practices to help minimize
proprietary name-related medication errors and otherwise avoid adoption of proprietary names
that contribute to violations of the Federal Food, Drug, and Cosmetic Act (FD&C Act) and its
implementing regulations. It also describes the framework FDA uses in evaluating proposed
proprietary names that is also available to sponsors to use before submitting names for FDA
review if they wish. This guidance does not address the designation of established names or
proper names.
This guidance applies to all human prescription drug products. In this guidance, all such
products are jointly referred to as products, and persons responsible for developing the products
are referred to as sponsors.
FDA is separately developing guidance on best practices in developing proprietary names for
nonprescription drug products.4
1 This guidance was prepared by the Office of Surveillance and Epidemiology, Division of Medication Error
Prevention and Analysis, and the Office of Prescription Drug Promotion in the Center for Drug Evaluation and
Research (CDER), and the Advertising and Promotional Labeling Branch in the Center for Biologics Evaluation and
Research (CBER) at the Food and Drug Administration.
2 For purposes of this guidance, unless otherwise specified, references to “drugs” and “drug products” include drugs
submitted for approval or approved under section 505 of the FD&C Act (21 U.S.C. 355) and biological products
licensed under section 351 of the Public Health Service Act (42 U.S.C. 262), other than devices regulated under a
biologics license application.
3 Terms that appear in bold type upon first use are described in the Glossary, as they are used in this guidance.
4 See the FDA draft guidance for Industry Best Practices in Developing Proprietary Names for Human
Nonprescription Drug Products (December 2020) for design practices to help minimize errors with nonprescription
proprietary names. We update guidances periodically. For the most recent version of a guidance, check the FDA
Drugs guidance web page, available at
https://www.fda.gov/RegulatoryInformation/Guidances/default.htm.
When final, this guidance will represent the Agency’s current thinking on this topic.

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This guidance is intended to provide clarity and transparency to sponsors on the factors and
systematic framework FDA uses to evaluate proposed proprietary names for prescription drugs
and to recommend best practices for sponsors considering such names. Using the best practice
recommendations and other assessment tools addressed in this guidance is not mandatory, and
applying them does not dictate specific outcomes. Assessments of a proprietary name are
necessarily fact-specific, and therefore, FDA’s determinations are made on a case-by-case basis,
considering the totality of the information.
In general, FDA’s guidance documents do not establish legally enforceable responsibilities.
Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only
as recommendations, unless specific regulatory or statutory requirements are cited. The use of
the word should in Agency’s guidance means that something is suggested or recommended, but
not required.
II. 	BACKGROUND
Selecting a proprietary name is a critical element in drug product design and development
because end users may rely, in part or in whole, on the proprietary name to identify which
product, among thousands of available products, is intended for or used by a particular patient.
Proprietary names of drug products are commonly used by physicians and other health care
professionals to prescribe or discuss a drug, and for this reason, accurate identification by the end
user is essential. If end users cannot easily distinguish a proprietary name from other drug
names that are similar phonetically (sound-alike names) or in their spelling or orthographic
appearance (look-alike names), or if the drug name is otherwise confusing or misleading, the
patient might receive the wrong product, or it might not be possible to correctly identify the
product used.
A report released in 1999 by the Institute of Medicine (IOM) described medication errors as a
significant public health concern that accounts for an estimated 7,000 deaths annually in the
United States.5 The report recommended that FDA encourage pharmaceutical companies to test
proposed proprietary names to identify and remedy potential sound-alike and look-alike
confusion with existing drug names. 6 In July 2006, the IOM published a follow-up report titled
Preventing Medication Errors, which emphasized in part that proprietary name design should
focus on end users’ needs and understanding and urged FDA to apply the principles of cognitive
and human factors engineering to the selection and evaluation of proprietary names. 7,8
5 IOM, 1999, To Err Is Human: Building a Safer Health System. Institute of Medicine, National Academies Press:
Washington, DC, 2000
6 IOM, 1999, To Err Is Human: Building a Safer Health System. Chapter 7, Recommendation 3, p. 136. The IOM
recommendations were consistent with an earlier FDA report that likewise underscored the importance of reducing
errors from proprietary name confusion. HHS/FDA Report to FDA Commissioner from the Task Force on Risk
Management titled Managing the Risks from Medical Product Use (May 10, 1999).
7,8 IOM, 2006, Preventing Medication Errors, Institute of Medicine, National Academies Press: Washington, DC,
2000, Chapter 6, Recommendation 4, p. 274. pp. 281-282.

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As FDA has long recognized, and addressed on numerous occasions in recent decades, confusion
involving proprietary names can cause or contribute to significant medication errors.9 Our focus
has been to develop and communicate to sponsors a systematic, standardized, and transparent
approach to proprietary name evaluation within the product development, review, and approval
process. As part of this initiative, FDA held public meetings in June and December of 2003 to
discuss the methods used for proprietary name evaluation. In 2007, FDA formally committed to
certain performance goals, including implementing evaluation measures to help reduce medication
errors related to look-alike and sound-alike proprietary names (PDUFA IV) and in 2012
implemented BsUFA performance goals10,11 In 2008, the Agency held another public meeting to
further discuss testing and evaluating proprietary names.
This guidance, which we are issuing in partial fulfillment of the PDUFA IV performance goals,
presents FDA’s current thinking on best practices for developing and selecting proposed
proprietary names.
Proprietary names are used in a product’s label and labeling 12, including promotional labeling.
A drug’s labeling, in turn, is often a key element in FDA oversight. For example, under section
502(a) of the FD&C Act (21 U.S.C. 352(a)), a drug is misbranded if its labeling is false or
misleading in any particular. Section 201(n) of the FD&C Act (21 U.S.C. 321(n)) sets forth
certain considerations that shall be taken into account when determining whether labeling is
misleading. FDA regulations also address some of the ways in which the name of a drug may
render its labeling misleading.13 In addition, labeling is relevant to determining whether a drug
is a new drug under section 201(p) of the FD&C Act (21 USC 321(p)), for which premarket
approval is required (see sections 505(a) and 301(d) of the FD&C Act (21 U.S.C. 355(a) and
331(d)).
9 Smetzer, JL, and MR Cohen., 2007, The role of drug names in medication errors, in MR Cohen, Medication
Errors, 2nd ed., Washington, DC: American Pharmacists Association, pp. 87-110.
10 These performance goals and commitments were undertaken in connection with the reauthorization and expansion
of the Prescription Drug User Fee Act (PDUFA IV reauthorization), which was signed into law on September 27,
2007, as part of the Food and Drug Administration Amendments Act of 2007 (FDAAA) (Public Law 110-85). For
more information on FDA’s PDUFA IV performance goals, see FDA’s website at
https://www.fda.gov/ForIndustry/UserFees/PrescriptionDrugUserFee/ucm145390.htm.
11 These performance goals and commitments were undertaken in connection with the authorization of the
Biosimilar User Fee Act (BsUFA). For more information on FDA’s BsUFA performance goals, see FDA’s website
at https://www.fda.gov/industry/fda-user-fee-programs/biosimilar-user-fee-amendments
12 Labeling includes the prescribing information, container labels, carton labeling, and FDA-approved patient
labeling.
13 See, e.g., 21 CFR 201.6(b), stating that labeling for a drug containing two or more ingredients may be misleading
if the name of the drug designated in that labeling includes or suggests the name of one or more but not all of the
ingredients; 21 CFR 201.10(c)(3), stating that labeling of a drug may be misleading if it employs a fanciful
proprietary name for a drug or ingredient that implies some unique effectiveness or composition when the drug or
ingredient is in fact a common substance, the limitations of which are readily recognized when the drug or
ingredient is listed by its established name; 21 CFR 201.10(c)(5), stating that labeling of drug may be misleading if
the proprietary name may be confused with the proprietary name or established name of a different drug or
ingredient because of similarity in spelling or pronunciation.

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FDA reviews a proposed proprietary name as part of a prescription drug product’s labeling
through the application review process for the product.14 Although PDUFA and BsUFA
performance goals provide for the Agency to make a tentative determination of acceptance or
non-acceptance of a proposed proprietary name early in the review process (in instances where
the proprietary name review request is submitted as a complete submission), final acceptance of
a proposed proprietary name occurs as part of the approval of the drug product. Each name is
evaluated on a case-by-case basis.
Sponsors have an ongoing obligation to ensure that each marketed product satisfies applicable
requirements, such as ensuring that its labeling is not false or misleading in any particular (see
section 502(a) of the FD&C Act). If a marketed product’s proprietary name causes or
contributes to medication errors, the sponsor of that product should work expeditiously with
FDA to resolve the situation. If the product does not comply with applicable requirements and
the sponsor is unwilling to address or resolve an issue voluntarily, the sponsor may be subject to
enforcement actions.
The sections below outline considerations for developing and evaluating a proposed proprietary
name, which are described in greater detail in this guidance. Sections III and IV focus on
evaluating factors within the name or related to the naming strategy that are likely to contribute
to medication errors. Section V provides our recommendations for evaluating the proposed
proprietary name to help ensure compliance with FDA-administered statutory and regulatory
provisions, and section VI describes our current thinking on evaluating the proposed proprietary
names for look-alike and sound-alike risks.
For each category, we believe that no single test or standard is adequate to determine whether a
proposed proprietary name may contribute to errors or otherwise contribute to any violation of
the FD&C Act. Rather, the current approach to proposed proprietary name evaluation uses a
combination of different and complementary tests.
III. 	PRESCREENING PROPOSED PROPRIETARY NAME FOR ATTRIBUTES
THAT ARE LIKELY TO CONTRIBUTE TO MEDICATION ERRORS
This section identifies attributes of proposed human prescription drug product proprietary names
that FDA typically finds concerning and that generally can be identified through prescreening by
sponsors. We recommend that sponsors screen proposed proprietary names for the attributes
described below as a first step before proceeding with a full assessment of whether a name is
likely to contribute to medication errors or otherwise contribute to violations of the FD&C Act.
We recommend that sponsors avoid proposed human prescription drug product proprietary
names that raise concerns during preliminary screening. The sections below explain FDA’s
thinking on each of these aspects.
14 See FDA’s guidance entitled “Contents of a Complete Submission for the Evaluation of Proprietary Names”,
dated April 2016, available at https://www.fda.gov/media/72144/download.

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A. Obvious Similarities in Spelling and Pronunciation of Proprietary Names
FDA recommends that sponsors avoid proposed proprietary names that are similar in spelling or
pronunciation to existing proprietary names, established (or proper) names, or names of
ingredients of other products. A drug’s labeling may be misleading if its proprietary name is
similar in spelling and/or pronunciation such that it may be confused with the proprietary name
or the established name of a different drug or active ingredient (see § 201.10(c)(5) (21 CFR
201.10(c)(5))). FDA uses the Phonetic and Orthographic Computer Analysis (POCA) tool to
determine the similarity between names as detailed in section VI.C. Research has shown that
names involved in postmarketing medication errors generally have a higher degree of
similarity.15 Based on this research and our postmarketing experience, names with high
similarity scores are more likely to result in confusion. Generally, names that are nearly
identical in spelling and/or pronunciation generate a similarity score of 70% or higher on the
POCA tool. 16
B. Inert or Inactive Ingredients
We recommend that proposed proprietary names not incorporate any reference to an inert or
inactive ingredient (as defined in § 210.3(b)(8) (21 CFR 210.3(b)(8))), because doing so may
create a misleading impression that the ingredient’s value is greater than its true functional role
in the formulation (see, e.g., § 201.10(c)(4)).
C. Combinations of Active Ingredients
FDA recommends against proprietary names of fixed combination drug products that include or
suggest the name of one or more, but not all, of its active ingredients (as defined in §
210.3(b)(7)), because such names can mislead the end user by implying that the product contains
only the ingredient or ingredients included in, or suggested by the name (see 21 CFR 201.6(b) and
section 201(n) of the FD&C Act).
D. United States Adopted Name Stems
We recommend that sponsors avoid proprietary names that incorporate United States Adopted
Name (USAN) stems in the position that USAN designates for the stem in a nonproprietary or
established name. USAN stems are intended to indicate a pharmacological or chemical trait of a
drug, and a single stem may be applicable to multiple drug products. Using these stems in the
position designated by USAN within the proprietary names, when used inconsistently with the
intended USAN meaning, may imply that a product has a pharmacological or chemical trait that
it does not. Even when using these stems within the proprietary names is consistent with the
USAN meaning, it can result in the creation of multiple similar proprietary names and/or
proprietary names that are similar to the nonproprietary or established names for other drug
15 Lambert, BL, S-J Lin, K-Y Chang et al., 1999, Similarity as a risk factor in drug-name confusion errors: The look-
alike (orthographic) and sound-alike (phonetic) model, Medical Care, 37(12):1214–1225.
16 POCA Program, available at http://www.fda.gov/Drugs/ResourcesForYou/Industry/ucm400127.htm.

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products, leading to an increased risk of medication errors. We recommend as best practice that
sponsors screen proposed proprietary names against the stem list created by the USAN Council
to ensure that a USAN stem is not present in the stem position in the proprietary name.17
However, FDA is less concerned about USAN stems that consist of two letters in proprietary
names and would generally not object to their use. The two-letter stems are often not distinct
enough to be recognized as USAN stems. Also, some two-letter stems are outdated and have not
been used by the USAN Council for years. There are currently five stems that consist of two
letters as identified by the USAN Council.18
Two-letter stems have very few associations and, in some cases, are rarely used (e.g., –ac last
used by USAN Council in 1997 (nepafenac); -aj- only used once by USAN Council in 1976 for
lorajmine). We also note that USAN has used some of the two-letter stems in established names
(vortioxetine, afoxolaner), as well as included them in other stems (-tioxetine) that are
inconsistent with the cited stem definition. This has resulted in conflicting stems, and therefore,
in those instances, the stem does not support the USAN Council naming system or accurately
indicate the pharmacological or chemical trait of the drug. Additionally, based on our
postmarketing experience, the two-letter stems have not raised similar safety concerns that we
have identified with longer stems.19
FDA generally would not object to the inclusion of letters found within a USAN stem but located
within a position not reserved by USAN for the stem in a nonproprietary or established name,
because this likely would not create the same degree of risk for confusion as those names that
have the stem in the USAN-designated position.
In some cases, FDA may find a proposed proprietary name acceptable even if it includes a
USAN stem in the USAN-designated position. Such circumstances could arise if the proposed
name includes a word that can only be spelled in the English language using a stem in the
position designated by USAN. For example, if a proposed proprietary name includes the word
“congestion,” using the letters “gest,” which are a USAN stem, is unavoidable.
E. Brand Name Extension
In this guidance, FDA uses the term brand name extension to refer to a naming strategy that
uses a proprietary name that is already associated with one or more marketed drug products, with
or without a modifier, for a product that does not share any active ingredient(s) or active
moiety(ies) with the marketed product(s). Two examples of what FDA considers as brand name
extensions are:
17 See the list of approved USAN stems, available at: https://www.ama-assn.org/about/united-states-adopted-
names/united-states-adopted-names-approved-stems, last acessed 12/10/19
18 -ac: anti-inflammatory agents (acetic acid derivatives); -aj-: antiarrythmics (ajmaline derivatives); ef-: Fc fusion
protein; -fo-: phosphoro derivatives; and io-,-io-: iodine containing contrast media (accessed April 2, 2019).
19 Institute for Safe Medication Practices, 2003, Safety briefs: Aripiprazole or rabeprazole?, ISMP Med Saf Alert
Acute Care, 8(8):1-3;
Institute for Safe Medication Practices, 2002, Safety Briefs, ISMP Med Saf Alert Acute Care, 7(17):1-2.

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1. 	The proprietary name “Drugname” is already associated with a marketed product that
contains a specific active ingredient or active moiety, and the sponsor uses the same
proprietary name “Drugname,” with or without a modifier, to introduce a new product
that does not contain that same active ingredient or active moiety.
2. 	A sponsor uses a portion of the proprietary name already associated with a marketed drug
product (e.g., the use of a shared prefix letter string with a modified suffix letter string,
whereby the prefix letter string evokes the proprietary name already associated with a
marketed drug product), with or without a modifier, to introduce a new product that does
not contain the same active ingredient or active moiety.
FDA advises against using brand name extension to introduce a new product. Health care
professionals familiar with an existing product may, in some cases, equate that product’s
proprietary name with the product’s active ingredients (or active moieties) or uses.
In some cases, using the same proprietary name that is already associated with another marketed
drug product has led to the use of a product for the wrong indication, in the wrong patient
population, at the wrong dose, or in a contraindicated manner. Some of the errors caused by
these types of name confusions have resulted in serious adverse events when patients were
erroneously medicated with an active moiety that was not intended to be administered.
F. 	Reuse of Proprietary Names
FDA recommends that sponsors refrain from using the proprietary name of a product that is no
longer marketed to name a different drug product, because there is a strong risk that end users
may continue to associate the name with the original discontinued product. Prescribers often
continue to use the proprietary name of discontinued products. For example, when prescribing a
drug for which there are marketed generics, prescribers may refer to the proprietary name of the
discontinued brand version.20 Proprietary names associated with discontinued drug products also
may continue to appear in drug product reference texts and electronic media for extended periods
of time.
If proprietary names are proposed for reuse, FDA will assess them on a case-by-case basis,
considering factors that might establish the drug name familiarity, including length and extent of
product distribution, the existence (or lack thereof) of past or current generic equivalents, and
data that might otherwise show health care professional familiarity with the drug name. If a
sponsor chooses to use this approach in naming, we recommend sponsors consider the above
factors and provide data to support that reusing the proprietary name of a discontinued product
will not be problematic.
Note that in its evaluation of the proposed proprietary name for a new product, FDA does not
consider a proposed name to be “reused” if it is one that FDA previously found acceptable for a
20 Tu, CM, K Taylor, and G Chai. Use of proprietary names by prescribers for discontinued brand drug products
with existing generic equivalents, Drug Information Journal (published online August 21, 2012), available at
http://dij.sagepub.com/content/early/2012/08/21/0092861512456282.full.pdf+html, last accessed 12/10/19

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different product, but that was never used to market that earlier product. If submitted anew,
FDA will evaluate the acceptability of the name for the new product.
G. Use of Letters and Numbers That Are Unpronounceable as a Word in Proprietary
Names
Generally, as a best practice, proprietary names should be pronounceable as a word because
proprietary names are used by health care professionals when prescribing, ordering, transcribing,
dispensing, and administering drugs, and when counseling patients on their medications. We
discourage sponsors from proposing proprietary names that consist of a mixture of letters or
numbers placed together (e.g., IVS458). Such names may not be understood as drug names that
are typically composed of letters only, or they could be misconstrued as another element
associated with the drug product or prescription, such as dose or route of administration. Names
constructed in this manner could lead to medication errors depending on the nature of the
misinterpretation.
IV. 	ADDITIONAL BEST PRACTICES FOR EVALUATION OF PROPOSED
PROPRIETARY NAME
In addition to the preliminary screening recommendations described in section III, we
recommend that sponsors consider other important attributes described in this section during
name development and before proceeding with further assessment to reduce the likelihood that a
prescription drug’s proprietary name will contribute to medication errors or other violations of
the FD&C Act and its implementing regulations, either at the time of initial product launch or in
the event of future product development. FDA intends to evaluate each proposed proprietary
name for these attributes and determine its acceptability on a case-specific basis.
A. Names That Include Reference to Product-Specific Attributes
For flexibility in future product development and naming, FDA recommends that sponsors avoid
incorporating product-specific attributes, such as manufacturing characteristics (e.g.,
“NameLyophilized”), dosage form (e.g.. “Nametabs”) or route of administration (e.g.,
“Nameoral”), as part of the proposed root proprietary name. It is not uncommon for product-
specific attributes to change during a drug’s life cycle with subsequent introductions of new
dosing intervals, formulations, dosage forms, indications, and patient populations. If considering
a proprietary name that includes or refers to product-specific attributes, sponsors should be
mindful that future changes, such as changes in dosage form or route of administration, could
render the root proprietary name inaccurate and thus unusable for future formulations.
If references to product-specific attributes are included in the root proprietary name, FDA
recommends that the name be evaluated to ensure that the product-specific attribute is consistent
with the terminology used in the product’s labeling and does not pose risks for medication error.

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B. Medical Abbreviations
Sponsors are generally discouraged from incorporating symbols, dose designations, and medical
abbreviations commonly used for prescription communication in their proposed proprietary
name because their inclusion could inadvertently introduce a source of error.
We recommend consulting The Joint Commission’s “Do Not Use” list or the Institute for Safe
Medication Practices (ISMP) List of Error-Prone Abbreviations, Symbols, and Dose
Designations when considering the risk that a proposed proprietary name incorporating an
abbreviation, symbol, or dose designation in a proposed proprietary name will be subject to
misinterpretation.21,22
When evaluating a proposed proprietary name that contains an element that is also an
abbreviation, symbol, or dose designation, FDA recommends considering other factors such as
placement and presentation that may influence interpretation of the element to make sure the way
it is presented in the name is not error-prone. As an example, “po” has been used historically as
an abbreviation for oral route of administration in a medication order, typically appearing after
the drug name. Therefore, while the inclusion of letters “po” in the beginning or within the root
proprietary name (e.g. Poname or Napome) is unlikely to be misconstrued as a medical
abbreviation, and thus would not be expected to pose a risk for medication errors, if “po” is used
in the ending of the root proprietary name or as a modifier (e.g. Name PO or Namepo), this
would increase the likelihood of ”po” being misconstrued as an abbreviation for the oral route of
administration and thus create confusion if this is not the intended meaning.
C. Modifiers as Components of a Proprietary Name
Some proprietary names are constructed of a root proprietary name modified by added words or
components, which are referred to as modifiers. The modifier portion of a proprietary name
generally consists of one or more letters, symbols, numbers, and/or words, and appears at the
beginning or end of the root proprietary name, typically set off by a space or hyphen. Sponsors
frequently propose a shared root proprietary name with various modifiers to distinguish among
multiple products that contain at least one shared active ingredient.
Inconsistencies in the use of modifiers and the absence of a standardized meaning for some
modifiers that are meant to convey information about a product have been a source of confusion
to end users.23,24,25 For example, sometimes modifiers are used to convey distinguishing product
21 The Joint Commission’s Official “Do Not Use” List of Abbreviations, 2004, available at
http://www.jointcommission.org/assets/1/18/Official_Do_Not_Use_List_6_111.PDF, last accessed 12/10/19
22 The Institute for Safe Medication Practices’ (ISMP) List of Error-Prone Abbreviations, Symbols, and Dose
Designations, 2017, Horsham (PA), available at http://www.ismp.org/tools/errorproneabbreviations.pdf, last
accessed 12/10/19
23 Pennsylvania Patient Safety Authority. Drug Name Suffix Confusion is a Common Source of Errors. 2004
Dec;1(4):17-8
24 Institute for Safe Medication Practices. ISMP Medication Safety Alert! 2003 Oct;(8)21
25 Institute for Safe Medication Practices. ISMP Medication Safety Alert! 2003 Oct;(8)21

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characteristics, such as “Name ODT” (an orally disintegrating tablet) or “Name XR” (an
extended-release formulation). Confusion stemming from the use of modifiers in proprietary
names has led to medication errors, such as dispensing and administering wrong formulation,
wrong dose, wrong strength, or wrong frequency of administration. Medication errors have also
occurred within the same product line if the distinguishing modifier is omitted or disregarded
when a product is prescribed or dispensed.
To reduce such risks, FDA encourages sponsors that choose to use modifiers to select, whenever
possible, an existing modifier with an established meaning that has not been a source of
confusion (see Appendix A for examples of modifiers that, when intended to express the
accompanying meaning, have not been a source of confusion).
The following considerations are intended to help sponsors with this assessment:
1. 	General Considerations When Developing a Proprietary Name That May Include a
Modifier
 	Do you currently market one or more products under the proposed root
proprietary name?
o 	Proprietary names for prescription products that involve the use of family trade
names are evaluated on a case-by-case basis. Each request for review of a
proposed proprietary name that includes a family trade name will be evaluated to
consider whether the:
i. 	Products share at least one active ingredient or active moiety
ii. 	Products are differentiated by labeling (carton and container)
iii. 	Modifier conveys accurate information about the product
iv. 	Modifier effectively differentiates the product from other products in
the product line
In some cases, this naming practice has posed problems when the same root name
is used for multiple products without modifiers that adequately differentiate the
products.26 	The types of errors that have resulted from family trade name
confusion include, for example, the use of the product for the wrong indication,
the administration of an unnecessary active ingredient, and the use of a product in
the wrong patient population.
 	Does the product have a characteristic (e.g., extended-release formulation) that is
typically described by a modifier for other products that share that same
characteristic?
26 Institute for Safe Medication Practices, 2004, Safety Briefs: Caution: Dulcolax brand name extensions, ISMP Med
Saf Alert Acute Care, 9(7):1-2.

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In certain instances, a modifier associated with specific characteristics (such as XR
for extended-release formulations or ODT for orally disintegrating tablets) may be
beneficial even if no product with these characteristics is marketed under the same
root proprietary name. For example, there may be other immediate-release
formulations containing the active ingredient that are marketed under different root
names. In these cases, the addition of a modifier may provide incremental benefit
in signaling the correct route or manner of administration.
 	Where will the modifier be placed in relation to the root proprietary name? Are
there any conventions for the modifier placement that are used within the particular
drug product class?
o 	Although modifiers are usually placed at the end of the root name, there may be
certain instances in which the modifier is placed at the beginning of the root
name. For example, proprietary names of oral contraceptives often include
modifiers before the root name, such as Lo Simpesse, Tri-Linyah. In these cases,
the placement of modifiers is consistent with the established proprietary naming
practices for the class.
 	What is the risk of medication error resulting from omitting a modifier or
alternatively including a modifier that is misinterpreted as a medical term,
abbreviation, or other medical product name?27
o 	In some instances, analysis of the risk of errors related to the use of a modifier
may suggest that the use of an entirely distinct proprietary name for a product is
safer than the use of the same root proprietary name with a modifier (see section
IV.D for a detailed discussion of the risks). Such circumstances may arise when a
product under development will have significantly different indications and usage,
patient populations, dosages, safety profiles, or routes of administration from the
marketed product.
2. 	Additional and Special Considerations Related to Certain Types of Modifiers
In addition to the above general considerations that are applicable to all modifier
assessments, there are certain types of modifiers that are commonly used and warrant
special considerations as described below.
a. 	Descriptive modifiers
Some modifiers are composed of letters or words that are meant to convey information
about the product’s composition or use, and FDA refers to these as descriptive modifiers.
Examples would include the abbreviations in Appendix A and accompanying words to
27 See section VI for consideration on how to identify names with potential similarity to the proposed modifier.

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describe some aspect of the product (e.g., indication, formulation, patient population).
For example, the modifier “viscous” in Photrexa Viscous describes the formulation.
Potential for medication errors arises when descriptive modifiers are ambiguous,
misleading, or subject to misinterpretation. A primary factor in evaluating a modifier
associated with a proprietary name is whether the modifier’s intended meaning is
supported by the labeling and whether it is understood by the end user. Some factors to
consider are:
 	If the modifier is intended to convey information about a pertinent characteristic of
the product, does it accurately describe that characteristic?
 	What is the modifier’s intended meaning? Are there data from a label comprehension
study (or similar study) or data available from published literature to support that
health care professionals and consumers understand the intended meaning?
 	What is the risk if end users misinterpret the modifier’s intended meaning? What is
the impact of a medication error if an end user confuses the modifier with some other
element of a prescription or order (such as frequency, strength, route of
administration)? Alternatively, what is the risk if the modifier is omitted?
 	Is the proposed modifier currently used in the marketplace? We recommend
checking the ISMP’s current List of Products with Drug Name Suffixes and other
drug information references to determine whether the proposed modifier is already
used in the marketplace and whether it has been used consistently with a commonly
recognized meaning. 28 If an existing modifier with the same intended meaning is in
the marketplace and familiar to and understood by end users without error, FDA
recommends adopting that existing modifier. When deciding whether to use a
different modifier instead of an existing modifier with the same intended meaning,
consider whether the proposed modifier conveys the intended meaning as clearly as,
or more clearly than, the existing modifier.
b. 	Combination drug-device product modifiers
Some proprietary name modifiers represent the delivery device component of a
combination drug-device product. When the device component name is presented
contiguously with the drug component name and is part of the proposed proprietary
name, such modifiers are reviewed as part of the Center for Drug Evaluation and
Research’s (CDER’s) or the Center for Biologics Evaluation and Research’s (CBER’s)
proprietary name evaluation. Conventionally, for drug-device products with a drug
primary mode of action, the proprietary name of the drug component precedes the
proprietary name or modifier of the device component. For example, a product
integrating a drug and a disposable injector device might use a name such as “Drugname
Pen,” composed of the root proprietary name for the drug component followed by the
28 ISMP’s List of Products With Drug Name Suffixes internet, 2010. Horsham (PA): Institute for Safe Medication
Practices, available at http://www.ismp.org/Tools/drugnamesuffixes.pdf, last accessed 12/10/19

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modifier “pen” indicating the presence of the device component. Generally, modifiers
used with combination products that represent a device component are either (a) a
descriptive modifier that conveys the type of device such as “Pen,” “Prefilled Syringe,”
or “Inhaler” or (b) a sponsor-coined modifier, such as “SOLOSTAR” or “Diskus.”
A descriptive modifier may be suitable to use across different combination products
provided it accurately describes the combination product. Such descriptive modifiers
tend to convey in a general manner the category or type of device component (e.g.,
“Pen,” “Prefilled Syringe,” “Inhaler”). Although the device constituent part across
various combination products that use the same descriptive modifier may operate
differently and may contain different drugs, if the descriptive modifier is well understood
as describing a general category or type of device component to end users, FDA would
generally not have concern for confusion or errors.
Conversely, a sponsor-coined modifier may be well understood to represent a specific
device platform or technology. For these types of modifiers, sponsors may wish to use
the same modifier for a specific device platform across a number of drug-device
combination products, each containing different active moieties, to help prescribers and
end users understand the similar nature of the products. In such situations, FDA
generally will not object to this naming strategy if the drug component portions of the
proprietary names are adequately distinguishable and any differences in the operation of
the device across products is minor and otherwise not expected to result in errors.29
A final consideration for device modifiers used with drug-device combination products
relates to the introduction of a new device component that operates similarly, but not
identically, to a previously marketed device component that delivered the same drug
product. For example, if a sponsor is developing a drug-device combination product that
includes a new disposable injector device which introduces differences in critical tasks
that are likely to result in errors among prior users compared to an earlier marketed
device,30 a distinct modifier should be used to represent the new combination product in
order to communicate to prescribers and patients that the new combination product
operates differently from the earlier marketed combination product.
c. 	Use of numbers and symbols in modifiers
FDA generally recommends sponsors avoid the use of numbers within a proprietary
name. Both Roman and Arabic numbers have been mistaken for the strength, quantity,
29 It is likely that FDA would have concern with the use of a single sponsor-coined modifier across combination
products that do not operate similarly because it may mislead users and potentially lead to errors when administering
the product.
30 Critical tasks are those tasks that users must perform to safely and correctly use the product.

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duration, or controlled substance class of prescription drug products.31 ,32 For example,
when a drug order or prescription is written for a drug product with a proprietary name
that has the number “3” (to represent product strength) as part of its name, this might be
misinterpreted to mean that three tablets are to be dispensed or that the product should be
used for only 3 days. FDA also generally recommends against using symbols (e.g., “+”
or “&”) as part of proprietary names because symbols can be misinterpreted, misread, or
confused (e.g., “+” could be read as “4”).33 Therefore, as a best practice, FDA
recommends using words rather than symbols.
There are a few classes of drugs, however, for which there has been a historical practice
of using a slash (/) or hyphen (-), or of using numbers as modifiers, resulting in
established proprietary naming conventions for that class of drugs. In these cases, FDA
does not generally expect to object to proprietary names that include use of these
elements that are consistent with the established practice for the class. For example, the
proprietary names of oral contraceptives may include the use of a slash or hyphen (Tri-
linyah, Junel 1/20) or vaccines may include the valency (Myvaccine 10). There may be a
few instances where the use of numbers as modifiers minimizes the risk of errors and
promotes appropriate use of the products by conveying information to end users. For
example, the proprietary names of oral contraceptives often include numerical modifiers
to help differentiate among various strengths of the products. Similarly, the proprietary
names of insulin mixtures may use numerical modifiers to represent the proportion of
each type of insulin in the mixture.
D. Dual Proprietary Names
In certain cases, a modifier may not effectively convey a characteristic of the proposed product
or reliably differentiate the proposed product from other products that contain the identical active
moiety or ingredient(s). Such circumstances may arise when a product under development will
have significantly different indications and usage, patient populations, dosages, safety profiles,
or routes of administration from the marketed product. For example, two products may be
administered using different routes of administration, or have differing doses, which may present
a risk of medication errors to a population taking the product for a second indication. In these
unique instances, the use of two different proprietary names (also referred to as dual proprietary
name) may be a safer naming approach. However, sponsors should also consider the risks
associated with this naming strategy. For example, practitioners may be unaware that two
products with different proprietary names prescribed for concomitant use contain the same active
ingredient. This could lead to overdose or dose-related adverse events. Another risk may be if a
drug-drug interaction is not noted because the health care professional and patient are unaware
that a product sold under one proprietary name contains the same active ingredient as another
31 Institute for Safe Medication Practices. Misidentification of alphanumeric characters. ISMP Medication Safety
Alert! Community/Ambulatory Care Edition. 2014 Jun; (19)11.
https://www.ismp.org/resources/misidentification-alphanumeric-symbols, accessed 1/13/20.
32 Institute for Safe Medication Practices. ISMP Medication Safety Alert! 2002 Jun; (7)13.
33 ISMP’s List of Error-Prone Abbreviations, 2010, Symbols, and Dose Designations. Horsham (PA): Institute for
Safe Medication Practices, available at: http://www.ismp.org/tools/errorproneabbreviations.pdf, last accessed
12/10/19

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product with a different proprietary name. Sponsors should assess the safest naming convention
for their situation and develop labeling and other measures to mitigate the risks associated with
dual proprietary names. FDA will evaluate these proposals on a case-specific basis along with
any associated labeling that might address these potential risks.
E. Proprietary Names of Drug Products Marketed Outside the United States
Medication errors resulting in dispensing and administering the wrong drug can occur when a
proprietary name for a product marketed in the United States is identical, or nearly identical in
spelling and pronunciation, to the proprietary name of a foreign product containing an entirely
different active ingredient marketed only in a foreign country. As seen in the example reported
by ISMP, a medication error occurred when a patient took digoxin instead of the intended
diltiazem product, both of which were marketed under the same proprietary name, Dilacor, in
different countries.34 For this reason, as a best practice, FDA recommends against proposing a
proprietary name that is identical or nearly identical to that of a marketed foreign product that
contains an entirely different active ingredient, even if the proposed product will be marketed
only in the United States (and even if the foreign product is not marketed in the United States).
F. 	Incorporation of the Sponsor’s Name
FDA recommends that sponsors avoid proposed proprietary names that incorporate the sponsor’s
name, or some part of the sponsor’s name, across multiple products (e.g., “ABCName1,”
“ABCName2,” “ABCName3”). This practice results in creating multiple similar proprietary
names, increasing the risk of confusion among the products. The practice could pose safety risks
when products are stored alphabetically in distributor or pharmacy locations or when products
are ordered from alphabetized lists.
V. 	FURTHER BEST PRACTICES FOR REVIEW, INCLUDING FOR
MISBRANDING AND OTHER LEGAL CONCERNS
Although this guidance focuses primarily on aspects of proprietary names that can contribute to
medication error, as a best practice, sponsors should avoid using a proprietary name that could
contribute to any violation of the FD&C Act. For example, among other things, the FD&C Act
provides that a drug is misbranded if its labeling is false or misleading in any particular (section
502(a)).
A proprietary name, which appears in labeling, could result in such misbranding if it is false or
misleading, such as by making misrepresentations with respect to safety or efficacy. For
instance, a fanciful proprietary name may misbrand a product by suggesting that it has some
unique effectiveness or composition when it is actually a common substance, the limitations of
which are readily recognized when the product is listed by its established name (see
§ 201.10(c)(3)). For example, a proposed proprietary name that contains cure or that sounds like
cure for a drug that treats the symptoms associated with a chronic disease would be concerning.
34 Institute for Safe Medication Practices, 2005, Safety briefs: Same name, different drug, ISMP Med Saf Alert
Acute Care, 10(1):2

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The word “cure” is defined as “something (such as a drug or medical treatment) that stops a
disease and makes someone healthy again” or “something that ends a problem or improves a bad
situation.” 35 Therefore, if a proposed proprietary name for a chronic disease contains or sounds
like “cure,” it would overstate the clinical benefit by misleadingly implying that the product can
cure the chronic condition. As another example, a drug is a new drug if it is not generally
recognized as safe and effective (GRASE) for use under the conditions prescribed,
recommended, or suggested in its labeling (section 201(p) of the FD&C Act), and the
introduction of a new drug into interstate commerce without an approved application is
prohibited (sections 301(d) and 505(a) of the FD&C Act; see also section 351 of the PHS Act).
If the proprietary name of a drug suggests that it be used under conditions for which it is not
GRASE and for which it does not have an approved new drug application (NDA) or biologics
license application (BLA), distributing that drug with labeling bearing that proprietary name
would violate the FD&C Act.
In determining whether a name is misleading, common morphological and semantic associations
are considered along with phonesthemes (the sound of the name) and phonosemantics (meaning
conveyed by the sound of the word) of the name. 36 Research has shown that linguistic
characteristics can influence the way people perceive a product, particularly when it is new and
unfamiliar as is the case with newly proposed proprietary names. 37
If a sponsor chooses to review for concerns other than those likely to contribute to medication
errors, FDA recommends such a review be performed independent from a medication error
review to minimize bias in either review. The review should focus on identifying names that
overstate product efficacy or safety, expand product indications, suggest superiority without
substantiation, or are of a fanciful nature that misleadingly implies unique effectiveness or
composition. The analysis of sound empirical data, if available, should be given prominence in
evaluating proposed proprietary names.
One possible study methodology and some sample questions are outlined in Appendix B. These
sample questions are designed to guide sponsors in the development of outcome measures in
their studies but are not intended to be an exhaustive list. Sponsors are encouraged, but not
required, to seek advisory comments from the Agency on their proposed study methodology,
questionnaire, and analysis plan before collecting data.
35 “Cure,” Merriam-Webster.com (available at https://www.merriam-webster.com/dictionary/cure; accessed
April 3, 2019).
36 Bergen, B.K., 2004. The psychological reality of phonaesthemes, Language, 80:290-311.
37 Lowrey, TM, LJ Shrum, and TM Dubitsky, 2003, The relation between brand name linguistic characteristics and
brand name memory, Journal of Advertising, 32:7-17. See also Keller, KL, SE Heckler, and MJ Houston, 1998, The
effects of brand name suggestiveness on advertising recall, Journal of Marketing, 62:48-57. These researchers, for
example, conducted an experiment to investigate whether names that were suggestive of a particular characteristic of
the product increased the recall and therefore the success of the communication. They found that participants better
recalled suggestive names for characteristics relevant to the product (e.g., a television’s picture quality;
PicturePerfect) than those that were not suggestive (e.g., Emporium). Other researchers have found that even parts
of words or phonemes can influence perceptions and consumer judgments about unfamiliar names (Klink, RR, 2000,
Creating brand names with meaning: The use of sound symbolism, Marketing Letters, 11:5-20; Yorkston, E and G
Menon, 2004, A sound idea: Phonetic effects of brand names on consumer judgments, Journal of Consumer
Research, 31:43-51).
.

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VI. 	RECOMMENDED METHODS FOR EVALUATING RISKS OF MEDICATION
ERROR POSED BY SIMILARITY OF A PROPOSED PROPRIETARY NAME
TO OTHER NAMES
FDA’s review of proprietary names focuses on avoiding end user error. When evaluating a
proposed proprietary name, FDA considers many potential sources for error, including phonetic,
spelling, and orthographic similarities, as well as other sources of error identified elsewhere in
this guidance.
Specific methods that FDA uses to evaluate proposed proprietary names, as well as methods that
FDA recommends sponsors use before submitting a proposed proprietary name for FDA review,
are described below. The descriptions include methods for identifying existing proprietary
names or established names that could be confused with a sponsor’s proposed name, as well as
methods for assessing the likelihood and potential effects of name-related medication errors. If a
sponsor includes detailed study report(s) providing data from its own safety assessment(s) and
shows that these data were generated using a methodology that is generally consistent with that
described in this guidance, FDA intends to use these data to help evaluate the risk that the
proposed proprietary name would contribute to medication errors. Sponsors are encouraged to
conduct each of the types of assessments described below, but FDA considers what is submitted
on its individual merits, regardless of whether the assessment includes every type of testing
described below. 38
A. Name Simulation Studies
Name simulation studies conducted by FDA test how health care professionals employed by
FDA respond to the proposed names. The studies we conduct are limited in scope because they
involve only FDA staff. Although the sample size in FDA’s simulation studies is small, these
studies can provide important qualitative data that can be used to identify the potential
vulnerability of a proposed name to be misinterpreted. The likelihood of observing an error in a
small study is low, so that when an error is observed in a small study, this suggests that there will
be errors in actual use. However, small studies may not be sufficiently sensitive to reliably
identify all risks associated with a proposed proprietary name; the absence of observed errors in
small studies is not conclusive evidence that a proposed name will not be confused with another
38 Because sponsors do not have access to non-public information on pending proposed proprietary names, FDA
generally intends to use the methods described in this guidance to generate data to supplement any safety
assessments provided by sponsors using the methods described in section VI to evaluate the proposed proprietary
name for its potential to be confused with any non-public pending proposed proprietary names. FDA may use the
data identified from this supplementary evaluation of pending proposed name to determine if there are two or more
proprietary names under review that could result in medication errors caused by potential confusion with each other,
In these instances, FDA will notify both applicants of the conflict.

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drug product’s proprietary name. For these reasons, FDA believes it would be useful for
sponsors to conduct more comprehensive simulation studies.
Appendix C outlines elements that are recommended for consideration if sponsors choose to
conduct simulation studies.
B. Obtain Medication Error Data for Names That Are Already Associated With
Marketed Products
Case reports of medication errors related to proprietary names that are already associated with
marketed products can help inform the analysis of a proposed proprietary name. FDA monitors
medication error reports to identify cases of name confusion with the goal of identifying relevant
information about the causes of problems and failures that lead to medication error, and the
Agency applies any relevant information to the evaluation of a proposed proprietary name. FDA
recommends that sponsors obtain medication error report information from their internal safety
databases, publicly available VAERS (Vaccine Adverse Event Reporting System) or FAERS
(FDA Adverse Event Reporting System) data,39 published literature, and resources available
through patient safety organizations such as ISMP.
In some cases, there is marketing experience with the proposed proprietary name outside of the
United States. In these cases, if a sponsor obtains medication error information related to the
product’s established, proper, and/or proposed proprietary name that may be relevant to using the
proposed proprietary name in the United States, FDA recommends this information be provided
to FDA in the proprietary name submission.40
C. Computational Method To Identify Names With Potential Orthographic, Spelling,
and Phonetic Similarities
FDA evaluates the orthographic and phonetic similarity of a proposed proprietary name to other
names by using the POCA software.41 FDA enters the proposed proprietary name into FDA’s
POCA system and queries the proposed proprietary name against names in drug reference
databases (e.g., Drugs@FDA and RxNorm). Sponsors may include a POCA evaluation with
their proprietary name submissions; when included, FDA will use data from a sponsor’s POCA
evaluation to help evaluate the proposed proprietary name, provided that the methodology
employed to generate the data is generally consistent with the methods described below.
39 Available at
https://www.fda.gov/drugs/guidancecomplianceregulatoryinformation/surveillance/adversedrugeffects.
40 See 21 CFR 312.32(b). Sponsors are required to promptly review all information relevant to the safety of the drug
product obtained or otherwise received from any source, foreign or domestic, including information derived from any
clinical or epidemiological investigations, reports in the scientific literature, unpublished scientific papers, reports from
foreign regulatory authorities, and reports of foreign commercial marketing experience for drugs that are not marketed
in the United States.
41 On February 17, 2009 (74 FR 7450), FDA announced the availability of the source code and supporting technical
documentation for POCA software program royalty-free to the public.

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Regardless of whether a sponsor submits data from POCA for FDA to consider in its review,
FDA will independently conduct a review using POCA to compare the proposed proprietary
name to other proposed proprietary names submitted to the Agency for products not yet
approved. Such names are often confidential; therefore, it is possible that FDA may identify
conflicts with the names of pending products that are not publicly known to other sponsors
proposing proprietary names. 42
FDA recommends that sponsors screen their proposed proprietary names by conducting
orthographic and phonetic searches using the POCA system developed by FDA. We recommend
that you use POCA to search databases that encompass many drug products, such as
Drugs@FDA, and another database that captures a reasonable representation of nonprescription
drugs (e.g., RxNorm).
The threshold FDA uses to conduct the orthographic and phonetic searches is set at a combined
score of 55%, based on the validation work done on the POCA algorithms. Based on our
postmarketing experience, the combined measure of similarity has been positively correlated to
errors involving name confusion.
When using POCA, if the proposed name contains a modifier, first enter the root proprietary
name without the modifier and group the names as described below. Then repeat this process
using the root name and modifier. 43
The POCA search will provide three data sets: (1) COMBINED orthographic and phonetic
matches, (2) phonetic matches, and (3) orthographic matches. Sponsors should review the
COMBINED orthographic and phonetic matches and group the name pairs into one of the
following three categories:
 	Highly Similar Name Pair: combined match percentage score ≥70%
 	Moderately Similar Name Pair: combined match percentage score ≥55% to ≤ 69%
 	Low Similarity Name Pair: combined match percentage score ≤54%
As a general principle, the higher the percentage assigned by POCA, the greater similarity the
proposed proprietary name has to the name identified by POCA. Research has shown that names
involved in postmarketing medication errors because of prescribing or dispensing the wrong drug
have a higher degree of similarity than drug names that were not involved in these types of
42 Proposed names may be associated with drug products related to investigational new drug applications, NDAs,
biologics license applications, or abbreviated new drug applications. In those rare instances when a conflict is
identified with the proposed proprietary names of two pending drug applications, FDA will notify both Applicants
of the conflict in accordance with the Manual of Policies and Procedures: Procedures for Sharing Non-public
Information on Pending Proposed Proprietary Names, which is available at:
http://www.fda.gov/downloads/AboutFDA/CentersOffices/OfficeofMedicalProductsandTobacco/CDER/ManualofP
oliciesProcedures/UCM521551.pdf.
43 FDA only searches the combined root name and modifier in POCA if the total length of the name (root name +
modifier) is 10 letters or fewer. For modifiers located prior to the root name, e.g. Lo Ovral, Tri Sprintec, the entire
name is searched in POCA.

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medication errors.44 This research is corroborated by our postmarket surveillance of medication
errors and root cause analyses. Therefore, based on this research and postmarketing surveillance,
we expect names with high similarity scores to be more likely to result in confusion.
D. Safety Determination of Names With Potential Orthographic, Spelling, and
Phonetic Similarities
The acceptability of the proposed proprietary name from a look-alike and sound-alike
perspective is reviewed using the criteria outlined in checklists in Appendices D, E, and F, which
correspond to each of the three categories (Highly Similar Name Pair, Moderately Similar Name
Pair, and Low Similarity Name Pair) described in section VI.C. The intent of these checklists is
to increase the transparency and predictability of the safety determination of whether a proposed
proprietary name is vulnerable to confusion from a look-alike or sound-alike perspective. Each
bullet below corresponds to the name similarity category described in section VI.C. and cross-
references the respective Appendix that addresses criteria that FDA uses to determine whether
and to what extent a name presents a safety concern.
 	For highly similar name pairs, based on postmarketing experience, we know that
differences in product characteristics, including differences such as strength and dose,
often cannot mitigate the risk of a medication error. Therefore, proprietary name
pairs that are highly similar (i.e. have a combined score of ≥ 70%) are at greater risk
for a look-alike and sound-alike confusion,45 which is an area of concern for FDA
(see Appendix D).
 	Moderately similar name pairs should be further evaluated to identify the presence of
attributes that are known to cause name confusion.
o 	Name attributes: The first part of the drug name plays a significant role in
contributing to name confusion. Additionally, drug name pairs that start with the
same first letter and contain a shared letter string of at least 3 letters in both names
are a major contributing factor in the confusion of drug names.46 We evaluate all
moderately similar name pairs retrieved from POCA to identify the above
attributes. These name pairs are further evaluated to identify overlapping or
similar strengths or doses.
o 	Product attributes: Moderately similar name pairs of products that have
overlapping or similar strengths or doses represent an area of concern to FDA.
The dose and strength information is often located in close proximity to the drug
name on prescriptions and medication orders, and that information can be an
important factor that either increases or decreases the potential for confusion
44 Lambert, BL, S-J Lin, K-Y Chang et al., 1999, Similarity as a risk factor in drug-name confusion errors: The look-
alike (orthographic) and sound-alike (phonetic) model, Medical Care, 37(12):1214–1225.
45 We have also identified similar concerns with individual orthographic or phonetic POCA scores of ≥ 70%.
46 Shah, MB, L Merchant, IZ Chan et al., Characteristics that may help in the identification of potentially confusing
proprietary drug names, Therapeutic Innovation and Regulatory Science, 51(2): September 2016.

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between similarly drug-named pairs. The ability of other product characteristics
to mitigate confusion (e.g., route of administration, frequency of administration,
dosage form) may be limited when the strength or dose overlaps. FDA will
review such name pairs further to determine whether sufficient differences exist
to prevent confusion (see Appendix E).
 	Name pairs with low similarity are generally acceptable (see Appendix F) unless
there are data to suggest that the name might be vulnerable to confusion (e.g., name
simulation study suggests that the proposed proprietary name is likely to be
misinterpreted as that of a marketed product). In these instances, we would reassign a
low similarity name to the moderately similarity category and review accordingly
(see Appendix E).
In conclusion, FDA’s recommendations in this guidance are intended to help sponsors avoid
choosing a proprietary name that is likely to contribute to medication errors or otherwise
contribute to violations of the FD&C Act. In evaluating a proposed proprietary name, FDA
considers the information and analyses about the proposed proprietary name described in this
guidance, along with any additional name-related information submitted by the sponsor.
Assessments of a proprietary name are necessarily fact-specific, and therefore, FDA’s
determinations are made on a case-by-case basis, considering the totality of the information.

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GLOSSARY	1
2
The following terms are described only to assist in understanding how they are used in this	3
guidance, and are not intended for use outside the context of this guidance:	4
5
Active ingredient: An active ingredient is any component that is intended to furnish	6
pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or	7
prevention of disease, or to affect the structure or any function of the body of man or other	8
animals. The term includes those components that may undergo chemical change in the	9
manufacture of the drug product and be present in the drug product in a modified form intended	10
to furnish the specified activity or effect. See also 21 CFR 314.3(b).	11
12
Active moiety: An active moiety means the molecule or ion, excluding those appended portions	13
of the molecule that cause the drug to be an ester, salt (including a salt with hydrogen or	14
coordination bonds), or other noncovalent derivative (such as a complex, chelate, or clathrate) of	15
the molecule, responsible for the physiological or pharmacological action of the drug substance.	16
See also 21 CFR 314.3(b).	17
18
Adverse reaction: An adverse reaction is an undesirable effect, reasonably associated with use	19
of a drug, that may occur as part of the pharmacological action of the drug or may be	20
unpredictable in its occurrence. See also 21 CFR 201.57(c)(7).	21
22
Assimilation or deletion: Assimilation is a change of a sound in speech so that it becomes	23
identical with or similar to a neighboring sound. An example of assimilation is when the \z\	24
assimilates to \sh\ in the phrase his shoe. Deletion occurs when a sound is omitted in	25
pronunciation. Deletion usually occurs within the initial syllable of a word following at least one	26
consonant and followed by a stressed syllable. Examples of deletion would include garage to –	27
grage and surround to – sround. Deletion and assimilation can occur together, and often do, as	28
the assimilation of one feature of a neighboring sound will make that sound less phonologically	29
necessary and make its deletion more probable.	30
31
Brand name extension: FDA uses the term brand name extension to refer to a naming practice	32
that uses a proprietary name that is already associated with one or more marketed drug	33
products, with or without a modifier, for a product that does not share any active ingredient(s) or	34
active moiety(ies) with the marketed product(s).	35
36
Container closure system: A container closure system refers to the sum of packaging	37
components that together contain and protect the dosage form. This includes primary packaging	38
components and secondary packaging components, if the latter are intended to provide added	39
protection to the drug product. A packaging system is equivalent to a container closure system.	40
41
End user: The term end user includes, but is not limited to, the patient, patient’s caregiver,	42
prescribing physician, nurse, pharmacist, pharmacy technician, and other individuals who are	43
involved in routinely procuring, stocking, storing, prescribing, dispensing, and administering	44
medications (e.g., medication technicians).	45
46

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Established name: Section 502(e)(3) of the FD&C Act (21 U.S.C. 352(e)(3)) states that:	47
48
the term “established name,” with respect to a drug or ingredient thereof, means (A) the	49
applicable official name designated pursuant to section 508, or (B) if there is no such	50
name and such drug, or such ingredient, is an article recognized in an official	51
compendium, then the official title thereof in such compendium, or (C) if neither clause	52
(A) or clause (B) of this subparagraph applies, then the common or usual name, if any of	53
such drug or such ingredient, except that where clause (B) of this subparagraph applies to	54
an article recognized in the United States Pharmacopeia and in the Homeopathic	55
Pharmacopoeia under different official titles, the official title used in the United States	56
Pharmacopeia shall apply unless it is labeled and offered for sale as a homeopathic drug,	57
in which case the official title used in the Homeopathic Pharmacopoeia shall apply.	58
[emphasis added]	59
60
Family trade name: A family trade name results from a naming practice involving the use of a	61
shared proprietary name to market multiple products with a shared active ingredient, using a	62
suffix or modifier, to distinguish the products from one another. This practice is also referred to	63
as family branding.	64
65
Infix: An infix is a group of letters that appears in the middle of the proprietary name.	66
67
Label: As defined in section 201(k) of the FD&C Act (21 U.S.C. 321(k)), the term label means	68
“a display of written, printed, or graphic matter upon the immediate container of any article.” If	69
any word, statement, or other information is required by the FD&C Act to appear on the label, it	70
must appear on the outside container or wrapper, if there is one, or be “easily legible through the	71
outside container or wrapper.”	72
73
Labeling: As defined in section 201(m) of the FD&C Act, the term labeling means “all labels	74
and other written, printed, or graphic matter (1) upon any article or any of its containers or	75
wrappers, or (2) accompanying such article.”	76
77
Medication error: A medication error is any preventable event that may cause or lead	78
to inappropriate medication use or medication-related patient harm while the medication	79
is in the control of the healthcare professional, patient, or consumer. Such events may be	80
related to professional practice, health care products, procedures, and systems, including	81
prescribing, order communication, product labeling, packaging, and nomenclature,	82
compounding, dispensing, distribution, administration, education, monitoring, and use.47
	83
84
Modifier: A modifier is a portion of the proprietary name. Some proprietary drug names are	85
constructed of a root proprietary name and added word(s) or other components that are referred	86
to as the modifier portion of the proprietary drug name. The modifier portion of a proprietary	87
drug name might be a letter, number, word, device name, or combination of letters, numbers, and	88
words appearing at the beginning or end of a root proprietary name, typically set off by a space	89
or hyphen.	90
91
47 See also National Coordinating Council for Medication Error Reporting and Prevention, available at
https://www.nccmerp.org/about-medication-errors), last accessed on May 19, 2020

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Official compendium: The term official compendium is defined in section 201(j) of the FD&C	92
Act as “the official United States Pharmacopeia, official Homeopathic Pharmacopoeia of the	93
United States, official National Formulary, or any supplement to any of them.”	94
95
Packaging: A package or market package refers to the container closure system and labeling,	96
associated components (e.g., dosing cups, droppers, spoons), and external packaging (e.g.,	97
cartons or shrink wrap). A market package is the article provided to a pharmacist or retail	98
customer upon purchase and does not include packaging used solely for shipping such articles.	99
100
Prefix: A prefix is a group of letters that appears at the beginning of the proprietary name.	101
102
Proper name: For biological products, the term proper name means the nonproprietary name	103
designated by FDA in the license for a biological product licensed under the PHS Act. See also	104
21 CFR 600.3(k).	105
106
Proprietary name: The proprietary name of a drug product is its brand name 48
	107
108
Root proprietary name: Some proprietary names are constructed of multiple components.	109
When a proprietary name contains a modifier as one of the components, the non-modifier portion	110
of the proprietary name is referred to as the root proprietary name. The root proprietary name	111
may be shared by multiple products. An example of a root proprietary name for a prescription	112
drug product is Lantus in Lantus Solostar.	113
114
Serious adverse event: 	A serious adverse event is defined as an event that does or has the	115
potential to result in death, hospitalization, congenital abnormality, permanent disability, or	116
could be life-threatening. See also 21 CFR 314.80.	117
118
Suffix: A suffix is a group of letters that appears at the end of the proprietary name.	119
120
Vowel reduction: Vowel reduction is any of various changes in the acoustic quality of vowels,	121
which are related to changes in stress, sonority, duration, loudness, articulation, or position in the	122
word, and which are perceived as “weakening.” It most often makes the vowels shorter as well.	123
48 Sometimes referred to as the product’s “trade name”

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Databases and Other Resources	124
125
In most cases, the computerized resources listed here are publicly available.	126
127
FDA Adverse Event Reporting System (FAERS)	128
129
FAERS is a database that contains adverse event reports and medication error reports submitted	130
to FDA. The database is designed to support FDA’s postmarket safety surveillance program for	131
drug and therapeutic biologic products. The informatic structure of the FAERS database adheres	132
to the international safety reporting guidance issued by the International Council for	133
Harmonization. Adverse events and medication errors are coded using terms in the Medical	134
Dictionary for Regulatory Activities (MedDRA) terminology. More information about FAERS	135
can be found at https://www.fda.gov/drugs/surveillance/fda-adverse-event-reporting-system-	136
faers.	137
138
Vaccine Adverse Event Reporting System (VAERS)	139
140
VAERS is a postmarket vaccine safety surveillance program cosponsored by the Centers for	141
Disease Control and Prevention (CDC) and FDA. VAERS collects information about adverse	142
events that occur after the administration of U.S. licensed vaccines. The VAERS website	143
provides a nationwide mechanism by which adverse events following immunization can be	144
reported, analyzed, and made available to the public. The VAERS website also provides a	145
vehicle for disseminating vaccine safety-related information to parents or guardians, health care	146
professionals, vaccine manufacturers, state vaccine programs, and other constituencies. The	147
majority of VAERS reports are received from vaccine manufacturers and health care	148
professionals. More information about VAERS can be found at https://vaers.hhs.gov/.	149
150
Phonetic and Orthographic Computer Analysis (POCA)	151
152
POCA is a system designed by FDA and is publicly available by requesting the system from	153
FDA. 49 POCA is an analytical tool designed to help identify drug and biologic names that are	154
phonetically and orthographically similar to one another. The Alignment of Phonetic Sequences	155
(ALINE) algorithm is used to calculate the phonetic score. The orthographic component of the	156
current algorithm was revised in December 2016 to accommodate the changing trends in	157
medication errors due to technological changes. The revised new algorithm is designed to better	158
capture the shift in the type of errors that are being reported due to using electronic prescribing.	159
The algorithm has been revised to put more emphasis on similarity that occurs at the beginning	160
of the word, especially the first three letters (bigram or trigram), and on exact letter matches.	161
The algorithm continues to have emphasis on consecutive exact matches but also emphasizes	162
where names share letters that are not consecutive. Several new score metrics (i.e., sub-	163
algorithms) are combined in various ways to formulate the final score.50
	164
49 Available at https://www.fda.gov/drugs/information-industry-drugs/phonetic-and-orthographic-computer-
analysis-poca-program.
50 Modified Adaptive Algorithm: Modified the existing bi-gram matching algorithm to account for reverse confuse
lookups. Initial Match: Check up to first n matching letters. This is to accommodate beginning letter(s) overlap.

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165
POCA search provides three data sets: (1) combined orthographic and phonetic matches, (2)	166
phonetic matches, and (3) orthographic matches. The threshold FDA uses to conduct the	167
orthographic and phonetic searches is set at a combined score of 55%, based on the validation	168
work done on the POCA algorithms.	169
170
Drugs@FDA	171
172
Drugs@FDA, is an FDA website that contains most of the drug and therapeutic biological	173
products approved in the United States since 1939. The majority of labeling, approval letters,	174
reviews, and other information are available for products approved from 1998 to the present.	175
Drugs@FDA contains information about FDA-approved brand name and generic drugs;	176
therapeutic biological products, prescription and over-the-counter human drugs; and	177
discontinued drugs. See Drugs@FDA, available at	178
https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm.	179
180
RxNorm	181
182
RxNorm is publicly available and contains the names of prescription and many OTC drugs	183
available in the United States. RxNorm includes generic and branded drug products and	184
packaging configurations. Radiopharmaceuticals, contrast media, food, dietary supplements, and	185
medical devices, such as bandages and crutches, are not included in RxNorm (see RxNorm,	186
available at http://www.nlm.nih.gov/research/umls/rxnorm/overview.html#).	187
188
USAN Stems	189
190
The USAN Council (tri-sponsored by the American Medical Association (AMA), the United	191
States Pharmacopeial Convention, and the American Pharmacists Association) aims for global	192
standardization and unification of drug nomenclature and related rules to ensure that drug	193
information is communicated accurately and unambiguously. The USAN Council works closely	194
with the International Nonproprietary Name Programme of the World Health Organization, and	195
various national nomenclature groups. The website is publicly available, managed by the AMA,	196
and contains lists of all the recognized USAN stems (available at https://www.ama-	197
assn.org/about/united-states-adopted-names/united-states-adopted-names-approved-stems).	198
199
Medical Abbreviations References	200
201
Various references on this topic are available. These references contain commonly used medical	202
abbreviations and their definitions.	203
Longest Common Subsequence: the longest group of letters from two words that are common between the two
groups and in the same order in each group. Unigram Match: This metric gives priority to overlapping letters fixed
in the same position. Longest Common Substring: This metric gives priority to drug names embedded within another
drug name.

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Appendix A: Examples of Previously Used Modifiers and Their	204
Commonly Understood Meanings	205
206
Modifiers 	Meaning
XR 	Extended-release product
ER 	Extended-release product
DS 	Double strength
LA 	Long acting
Pak
For example, dose card package or
carton containing two or more
drugs
Depot 	Depot injection
ODT 	Orally disintegrating tablets
Lo
Used as a modifier before the root
name in oral contraceptives to
indicate low-dose estrogen
Tri
Used as a modifier before the root
name in oral contraceptives to
indicate triphasic oral
contraceptive
Fe
Used to indicate ferrous
component
207

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Appendix B: Research Methodology for Conducting	208
Misbranding Review	209
210
For sponsors that wish to submit data on a proposed proprietary name, FDA recommends an	211
experimental method as part of the approach to determine whether a proposed proprietary name	212
is misleading because this method enables interpretation of causal relationships between	213
variables. That is, by controlling all other experimental factors besides the drug name,	214
researchers can be confident that the name itself caused particular responses. Box 1 provides one	215
possible approach for such an evaluation. Other approaches may be appropriate. The approach	216
described in Box 1 should be especially helpful in gathering information about how a name	217
influences attitudes and behaviors of a practicing health care professional. If participants are	218
only asked what they think about the proposed name, it will be difficult to determine how	219
accurately their responses reflect their actual thoughts or likely behaviors, because participants	220
may state what they think they should state, or what they think the investigators want to hear.	221
Comparing the responses to the proposed name with responses to the neutral control name,	222
however, could determine whether the proposed name influences these thoughts and intended	223
behaviors.	224
225
a. 	Design of Questions	226
227
A combination of open-ended and closed-ended questions, arranged from more general to more	228
specific, should be used. Questions should be designed to avoid leading questions, yea-saying	229
and other forms of bias.1 Initial questions in the study should be asked before participants have	230
any information about the product so that the answers will not be influenced by knowledge of	231
product characteristics. Subsequent questions would be asked after receiving indication	232
information for the product but no other identifying information. Because investigational new	233
drug (IND) studies form the basis of ultimate determinations about the efficacy and risk of a drug	234
product seeking approval, specifics may not be known at the time the proprietary name is	235
proposed and undergoing testing. Therefore, there should be a measure of participant response	236
when participants have only minimal information.	237
238
239
240
Box 1: Possible Evaluation Design	241
242
243
244
245
246
247
248
249
250
1 For a brief discussion of questionnaire bias in label comprehension studies, see Morris, L.A., Lechter, K.,
Weintraub, M., et al., Comprehension testing for OTC drug labels: Goals, methods, target population, and testing
environment. Journal of Public Policy and Marketing. 1998;17(1):86-96.

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251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
Examples of questions include:	293
• You have just learned of a new product named DRUG X. What, if anything, does the	294
name DRUG X say or suggest to you about the product? (open-ended question)	295
The FDA recommends as one possible approach a crossover design in which
the proposed proprietary name is evaluated in the context of both a neutral
control name and an extreme control name. This involves splitting the study
participants into two groups, both of whom will evaluate the proposed
proprietary name but in a different order from each other.
Before testing the proposed proprietary name, two control names should be
established through pretesting:
 	A neutral control name that is pretested to ensure that it makes no
representations at all (i.e., it is neutral from a promotional standpoint)
should be established.
 	An extreme control name that is pretested to ensure it makes clear
misrepresentations should be established.
All the participants will respond first to questions about the neutral control
name, described above. Next, half of the participants respond to the proposed
name and then to the extreme control name described above. The other half of
the participants respond to the extreme control name first and then to the
proposed name.
The study questions used as outcome measures should cover perceptions
elicited by the proposed name that are of a promotional nature (e.g., product
safety, efficacy, indication, superiority), as well as questions designed to elicit
aspects of behavioral intent (e.g., likelihood to prescribe). A comparison of
interest is participant responses to the proposed name compared with responses
to the neutral control name. The extreme name serves as a positive control to
ensure that individuals can identify names that make representations about
efficacy, safety, or other promotional aspects.
The FDA suggests that the neutral and extreme names be fictitious in nature to
control for participants’ prior experience and attitudes. Existing names could
be acceptable as neutral or extreme controls if they are pretested and shown to
possess the desired experimental qualities outlined above.
Sponsors may choose to select different neutral and extreme control names for
each study, or they may choose to use the same neutral and extreme control
names for multiple studies. Participants should be exposed to the neutral
control name only once across studies; that is, sponsors that choose to use the
same neutral name in more than one study should choose a new set of
participants for that study to ensure that participants have not previously
responded to the neutral name.

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• Based on this name, which of these conditions do you think DRUG X treats? (please	296
choose the best answer) (closed-ended question)	297
- Condition 1	298
- Condition 2	299
- Condition 3	300
- Condition 4	301
• Based on this name, how effective or ineffective would you say DRUG X is?	302
- Very effective	303
- Somewhat effective	304
- Somewhat ineffective	305
- Very ineffective	306
• Based on this name, how safe or unsafe would you say DRUG X is?	307
- Very safe	308
- Somewhat safe	309
- Somewhat unsafe	310
- Very unsafe	311
• Now you learn that product DRUG X is used to treat CONDITION Y. What does this	312
name mean to you in this context?	313
Based on this name, how safe or unsafe would you say it is to use DRUG X to treat	314
CONDITION Y?	315
- Very safe	316
- Somewhat safe	317
- Somewhat unsafe	318
- Very unsafe	319
Based on this name, how effective or ineffective would you say DRUG X is to treat	320
CONDITION Y?	321
- Very effective	322
- Somewhat effective	323
- Somewhat ineffective	324
- Very ineffective	325
• If DRUG X were available, how likely would you be to prescribe DRUG X for	326
CONDITION Y?	327
- Not at all likely	328
- Somewhat likely	329
- Moderately likely	330
- Very likely	331
• On a scale from 1 to 5, where 1 equals Strongly Disagree and 5 equals Strongly Agree,	332
please indicate your agreement or disagreement with the following statement:	333
This name suggests superiority over other products with the same indication.	334
335

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b. 	Sampling	336
337
These are general comments. A statistician should be consulted before making definitive	338
determinations about sample size and sampling design. The size of the study participant sample	339
should be adequate to detect differences. The sample should represent the relevant prescribing	340
population and be generalizable to this population. In addition, sponsors should consider testing	341
a sample of consumers. Although this group does not have prescribing authority, consumers	342
should and do participate actively in treatment decisions. The product name may play a role here	343
through direct-to-consumer advertising.	344
345
c. 	Submission to FDA	346
347
If submitting data on a proposed proprietary name, sponsors should submit to the appropriate	348
center for evaluation of all research methodology used to support that proposed proprietary	349
name. This includes a description of participant demographics; the study methodology	350
(protocol); the product profile provided to study participants; the complete study questionnaire,	351
including any screening questions; the coding scheme used to analyze open-ended questions;	352
complete study results (both positive and negative), including results of pretests; and any other	353
information given to the study participants regarding the drug approval process (e.g., copies of	354
FDA regulations given to study participants).	355
356
357

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Appendix C: Research Methodology Considerations for	358
Conducting Name Simulation Studies	359
360
Generally, name simulation studies test how subjects respond to a proposed proprietary name by	361
asking them to use the name in use conditions that simulate the real world. The more closely and	362
fully the simulation approximates real-world use conditions, the more generalizable the results of	363
the simulation testing. Name simulation tasks should reflect the full range and variety of tasks	364
involved in the prescribing, transcribing, dispensing, and administering of drugs. Simulations	365
should include common characteristics of real use, such as using ruled or unruled paper,	366
prescription pads, computer order entry, and telephone orders to approximate written, oral, and	367
electronic prescribing in the setting of care for the proposed product (e.g., inpatient and	368
outpatient settings, long-term care). Simulations should approximate the diversity of real-world	369
prescribing conditions by varying factors such as background noise, handwriting samples,	370
different ink colors, directions for use, and different voices/accents. In addition, the simulation	371
study should present the proprietary name with the corresponding product characteristics (e.g.,	372
strength, route, dosage, and frequency) that are likely to be used to communicate prescriptions	373
and orders for the proposed product. For example, when considering a product that is dosed on	374
milligram/kilogram basis, consider using an average weight-based dose for the intended	375
population in the simulation study.	376
377
a. 	Study Design	378
379
A simulation study designed to detect close to a zero percent error rate with statistical	380
significance would call for an extremely large sample size (e.g., a sample of ~26,000 to detect an	381
error rate of 0.001 at the 0.05 significance level).2 FDA recognizes that a study of this	382
magnitude is not realistic. However, a well-designed parallel group observational study	383
consisting of the participants described below can provide useful insight into how a proposed	384
proprietary name might perform in real-world conditions. In such a study, each group represents	385
different prescribing scenarios based on all the potential prescribing conditions for the proposed	386
product. We recommend that actively practicing health care professionals, such as prescribers,	387
medical transcribers, pharmacists, pharmacy technicians, or nurses, who administer the products	388
in the proposed use conditions for the product be included in the study.	389
390
When performing simulation testing, both quantitative and qualitative data should be collected.	391
Both types of data can be collected anywhere in the medication-use system. For example,	392
quantitative data might document how many times a participant interpreted a prescription	393
correctly and how many times it was misinterpreted. Qualitative data should include any	394
concerns or problems the participants thought of or encountered while going through the process	395
(for example, no error occurred but a participant felt that an error could have occurred in the	396
situation). For a name that was misinterpreted, data should include whether the name was	397
misinterpreted as another drug name or whether there were trends in spelling misinterpretations	398
for specific letters.	399
400
2 This calculation was made to determine whether the error rate differs from 0.001 at a 0.05 significance level and
80% power, assuming the medication error rate of the sample is 0.0005.

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b. 	Participants	401
402
All participants in name simulation studies should be actively practicing health care	403
professionals, such as prescribers, medical transcribers, pharmacists, pharmacy technicians, or	404
nurses, who administer the products in the proposed use conditions for the product. Sponsors	405
should take care to ensure that participants are representative of the full range of persons	406
involved in a given scenario. The study should simulate the full range of settings where the	407
product could be used, such as community pharmacy, ambulatory care, hospital, or long-term	408
care. For example, if the product will be dispensed in an inpatient setting, the participants should	409
include, but not be limited to, inpatient pharmacists, pharmacy technicians, ward clerks, and	410
nurses. When evaluating proprietary names for specialty drugs, sponsors should consider	411
whether the specialty drug could be at risk for entering into broader health care contexts. If so,	412
sponsors should consider including primary care practitioners, pharmacists, pharmacy	413
technicians, and nurses to probe which product names outside the specialty might cause error.	414
These stakeholders will bring experience from different workflow and practice environments.	415
416
c. 	Number of Scenarios	417
418
For an adequate descriptive assessment, sponsors should test an adequate number of scenarios to	419
provide a concomitant benefit in accuracy and reliability of the study outcomes. Scenarios may	420
vary depending on the type of setting and should be appropriate for the product being tested.	421
Participants involved in a name simulation study can participate in the testing of multiple	422
proposed proprietary names. However, to minimize bias, a name should be tested only once by	423
the same participant in the written and spoken scenarios.	424
425
Each anticipated prescribing condition for the proposed product should be tested several times,	426
considering all relevant modes of communication (such as spoken, written, computer order entry,	427
computer selection, and selection of product from drop-down menu). For example, for a product	428
that is administered only intravenously in an inpatient setting, an outpatient simulation using a	429
handwritten prescription might not be helpful. A simulation for an orally administered product	430
that could be dispensed in either inpatient or outpatient settings should contain all possible	431
inpatient and outpatient scenarios. When appropriate, these scenarios should be revised to	432
reflect, as closely as possible, the likely health care setting(s) for using the product, including	433
how the product will be prescribed, how the prescription will be transcribed, and how the	434
product will be dispensed and administered.	435
436
Sponsors should consider embedding the test name in a list of two or three other proprietary	437
names of marketed products in the simulated prescriptions, or consider using other simulated	438
prescription formats that are designed to mimic actual use. Spoken orders should include several	439
scenarios with an unaided pronunciation and several scenarios with a pronunciation based on	440
how the sponsor proposes to pronounce the name when marketed (for example, Kaletra is	441
pronounced by some as Kuh-let-ra and the sponsor’s pronunciation is Kuh-lee-tra).	442
443
At the end of a simulation, each participant should be interviewed, preferably using nonleading	444
scripted follow-up questions. The participant responses should be recorded verbatim. All	445
qualitative data derived from follow-up questioning should be coded and analyzed. The	446

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verbatim responses might confirm or further describe a potential for confusion. More	447
importantly, responses might identify additional names of concern that were not identified	448
through a manual database or computational searches. The names identified from the simulation	449
study should then be evaluated as outlined in section IV of this guidance to assess the likelihood	450
of confusion with the proposed name.	451

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Appendix D: Highly Similar Name Pair Checklist	452
453
Highly Similar Name Pair Checklist (i.e., COMBINED Orthographic/Phonetic score is ≥ 70%)	454
455
Answer the questions in the checklist below. Affirmative answers to some of these questions
suggest that the pattern of orthographic or phonetic differences in the names may render the
names less likely to confusion, provided that the pair do not share a common strength or dose.
Orthographic Checklist 	Phonetic Checklist
Y/N
Do the names begin with
different first letters?
Note that even when names
begin with different first letters,
certain letters may be confused
with each other when scripted .
Y/N
Do the names have
different number of
syllables?
Y/N
Are the lengths of the
names dissimilar when
scripted or printed?
FDA considers the length of
names different if the names
differ by two or more letters.
This may be dependent on the
position of the letters within the
name and which letters are
used. Some letters are more
noticeable than others (e.g.,
“m” is a wide, noticeable
letter).
Y/N
Do the names have
different syllabic
stresses?
Y/N
Considering variations in
scripting of some letters
(such as z and f), is there a
different number or
placement of
upstroke/downstroke
letters present in the
names?
Y/N
Do the syllables have
different phonologic
processes, such as
vowel reduction,
assimilation, or
deletion?
Y/N
Is there different number
or placement of cross-
stroke or dotted letters
present in the names?
Y/N
Across a range of
dialects, are the names
consistently
pronounced
differently?
Y/N
Do the infixes of the
name appear dissimilar
when scripted?
Y/N
Do the suffixes of the
names appear dissimilar
when scripted?

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41
Appendix E: Moderately Similar Name Pair Checklist	456
457
Moderately Similar Name Pair Checklist (i.e., combined score is ≥55% to ≤69%)	458
459
Step 1 	Review the DOSAGE AND ADMINISTRATION and HOW
SUPPLIED/STORAGE AND HANDLING sections of the Prescribing
Information to determine whether strengths and doses of the name pair overlap
or are very similar. Different strengths and doses for products whose names are
moderately similar may decrease the risk of confusion between the moderately
similar name pairs. Name pairs that have overlapping or similar strengths or
doses have a higher potential for confusion and should be evaluated further (see
Step 2). Because the strength or dose could be used to express an order or
prescription for a particular drug product, overlap in one or both of these
components would be reason for further evaluation.
For single-strength products, also consider circumstances where the strength may
be omitted.
For any drug products comprised of more than one active ingredient, consider
whether the strength or dose may be expressed using only one of the
components.
To determine whether the strengths or doses are similar to your proposed
product, consider the following list of factors that may increase confusion:
o 	Alternative expressions of dose: for example, 5 milliliters (mL) may
be listed in the Prescribing Information, but the prescription may
express the dose in metric units (e.g., 500 milligrams (mg)) or in non-
metric units (e.g., 1 teaspoon, 1 tablet/capsule). Similarly, a strength
or dose of 1,000 mg may be expressed, in practice, as 1 gram, or vice
versa.
o 	Presence of trailing zeros or absence of leading zeros: for example,
10 mg (if written as 10.0 mg) is similar in appearance to 100 mg,
which may potentiate confusion between a name pair with moderate
similarity. Additionally, 0.1 mg can be confused with 1 mg if written
without a leading zero (.1 mg).
o 	Similar sounding doses: for example, 15 mg is similar in sound to
50 mg.
460
461

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41
462
Step 2 	Answer the questions in the checklist below. Affirmative answers to some of
these questions suggest that the pattern of orthographic or phonetic differences in
the names may reduce the likelihood of confusion for moderately similar names
with overlapping or similar strengths or doses.
Orthographic Checklist
(Y/N to each question)
 	Do the names begin with
different first letters?
Note that even when names begin
with different first letters, certain
letters may be confused with each
other when scripted .
 	Are the lengths of the names
dissimilar when scripted?
FDA considers the length of names
different if the names differ by two
or more letters.
 	Considering variations in
scripting of some letters (such
as z and f), is there a different
number or placement of
upstroke/downstroke letters
present in the names?
 	Is there different number or
placement of cross-stroke or
dotted letters present in the
names?
 	Do the infixes of the name
appear dissimilar when
scripted?
 	Do the suffixes of the names
appear dissimilar when
scripted?
Phonetic Checklist
(Y/N to each question)
 	Do the names have different
number of syllables?
 	Do the names have different
syllabic stresses?
 	Do the syllables have different
phonologic processes, such as
vowel reduction, assimilation,
or deletion?
 	Across a range of dialects, are
the names consistently
pronounced differently?
463

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40
Appendix F: Low Similarity Name Pairs	464
465
Low Similarity Name Pairs (i.e., combined score is ≤54%)	466
467
 	Names with low similarity are generally acceptable unless there are data to
suggest that the name might be vulnerable to confusion (e.g., prescription
simulation study suggests that the name is likely to be misinterpreted as a
marketed product). In these instances, we would evaluate the name pair as
moderate similarity and review according to the moderately similar name pair
checklist (see Appendix E).
468
469
470