ANDA Submissions — Refuse to Receive for Lack of Justification of Impurity Limits: Guidance for Industry

Administrative guidance, not enacted legislation. This captured publisher edition preserves the listed document and attachments; later developments are not independently consolidated.

ANDA Submissions –
Refuse to Receive for
Lack of Justification of
Impurity Limits
Guidance for Industry
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
August 2016
Generics

ANDA Submissions –
Refuse to Receive for
Lack of Justification of
Impurity Limits
Guidance for Industry
Additional copies are available from:
Office of Communications
Division of Drug Information, WO51, Room 2201
Center for Drug Evaluation and Research
Food and Drug Administration
10903 New Hampshire Ave., Silver Spring, MD 20993-0002
Phone: 301-796-3400; Fax: 301-847-8714
druginfo@fda.hhs.gov
http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
August 2016
Generics

Contains Nonbinding Recommendations
TABLE OF CONTENTS
I. INTRODUCTION............................................................................................................. 1
II. BACKGROUND ............................................................................................................... 2
III. JUSTIFYING IMPURITY LIMITS IN DRUG SUBSTANCES AND PRODUCTS . 3
A. Refusal to Receive for Lack of Impurities Information ............................................................. 3
B. Providing Justification for Impurity Limits ................................................................................ 4

Contains Nonbinding Recommendations
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ANDA Submissions – Refuse to Receive for Lack of Justification of
Impurity Limits
Guidance for Industry1
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
This guidance is intended to assist applicants preparing to submit to the Food and Drug
Administration (FDA) original abbreviated new drug applications (ANDAs) and prior approval
supplements (PASs) to ANDAs for which the applicant is seeking approval of a new strength of
the drug product.2 The guidance highlights deficiencies in relation to information about
impurities that may cause FDA to refuse to receive (RTR) an ANDA.3,4 An RTR decision
indicates that FDA determined that an ANDA is not sufficiently complete to permit a substantive
review.5
Typical deficiencies leading to an RTR decision include: (1) failing to provide justification for
proposed limits in drug substances and drug products for specified identified impurities that are
above qualification thresholds; (2) failing to provide justification for proposed limits for
specified unidentified impurities that are above identification thresholds; and (3) proposing
limits for unspecified impurities (e.g., any unknown impurity) that are above identification
thresholds.
This guidance is not meant to be a comprehensive list of deficiencies in relation to impurity
information that may or will lead FDA to make an RTR determination. Rather, this guidance
clarifies that a failure to provide justification for proposed impurity limits may lead FDA to RTR
1 This guidance has been prepared by the Office of Generic Drugs in the Center for Drug Evaluation and Research
(CDER) at the Food and Drug Administration.
2 For purposes of this guidance, the use of the term ANDA will mean ANDAs and new-strength PAS submissions.
3 This should not be confused with a refuse-to-approve determination.
4 The following types of products are currently excluded from this guidance: (1) biological/biotechnologicals; (2)
peptides; (3) oligonucleotides; (4) radiopharmaceuticals; (5) fermentation products; (6) semisynthetic products
derived from fermentation products; (7) herbal products; (8) crude products of animal or plant origin; and (9)
enantiomeric impurities. For additional information on the applicability to ANDAs, see guidances for industry
ANDAs: Impurities in Drug Substances; ANDAs: Impurities in Drug Products; See also, guidances for industry
Q3A(R) Impurities in New Drug Substances (Q3A(R)); and Q3B(R2) Impurities in New Drug Products (Q3B(R2)).
5 21 CFR 314.101(b)(1).

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an ANDA. It also makes recommendations to ensure that applicants include appropriate
justification for impurities in their ANDA submissions.
In general, FDA’s guidance documents do not establish legally enforceable responsibilities.
Instead, guidances describe FDA’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 guidances means that something is suggested or recommended, but not
required.6
II. BACKGROUND
Pursuant to the enactment of the Generic Drug User Fee Amendments of 2012 (GDUFA),7 the
Office of Generic Drugs (OGD) is tasked with a number of activities, including the development
of “enhanced refusal to receive standards for ANDAs and other related submissions by the end
of year 1 of the program….”8 Enhanced RTR standards are important because the practice of
submitting an ANDA that is not sufficiently complete to permit a substantive review, which then
is “repaired” via several cycles of applicant resubmission and FDA response, is inherently
inefficient and wasteful of resources.
FDA evaluates each submitted ANDA individually to determine whether it can be received for
Agency review. FDA’s receipt of an ANDA means the Agency has made a threshold
determination that the ANDA is sufficiently complete to permit a substantive review.9 FDA’s
regulations at 21 CFR 314.101 provide the regulatory authority by which FDA may in certain
cases, and will in others, RTR an ANDA.10
Generally, FDA will not receive an ANDA for substantive review unless it contains the
information required under Section 505(j) of the Federal Food, Drug, and Cosmetic Act (FD&C
Act) and in 21 CFR 314.101 and other regulations, for example:11
 21 CFR 314.50
 21 CFR 314.94
 21 CFR 320.21
6 At various points this guidance notes that when FDA sees a particular type of deficiency in an ANDA it will RTR
the ANDA. It is important to understand that such statements do not impose legal obligations on applicants or on
FDA, but are included for purposes of transparency. This means that FDA, in the normal course, will RTR an
ANDA on the grounds described in this guidance. This guidance does not preclude the possibility that an ANDA
applicant may be able to demonstrate, in particular circumstances, that the regulatory requirements for receiving an
ANDA have been met even when, as described in this guidance, FDA would in the normal course find the
application not sufficiently complete and RTR it.
7 Generic Drug User Fee Amendments of 2012 (GDUFA), Public Law 112-144, Title III.
8 See Generic Drug User Fee Act Program Performance Goals and Procedures (the Commitment Letter):
http://www.fda.gov/downloads/ForIndustry/UserFees/GenericDrugUserFees/UCM282505.pdf.
9 See 21 CFR 314.101(b)(1).
10 See 21 CFR 314.101(d) -(e).
11 In certain cases, other statutes or regulations may apply.

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 21 CFR 320.22
This guidance focuses on when FDA expects to RTR an ANDA because it lacks justification for
proposed impurity limits.12
III. JUSTIFYING IMPURITY LIMITS IN DRUG SUBSTANCES AND PRODUCTS
All ANDAs must contain a description of the composition, manufacture, and specifications of
the drug substance and the drug product (see 21 CFR 314.94(a)(9) and 314.50(d)(1)). Applicants
are required to submit a full description of the drug substance including, but not limited to: its
method of synthesis (or isolation) and purification of the drug substance; the process controls
used during manufacture and packaging; and the specifications necessary to ensure the identity,
strength, quality, and purity of the drug substance (§314.50(d)(1)(i)). Applicants are also
required to submit a list of all components used in the manufacture of the drug product13
(regardless of whether they appear in the drug product) and a statement of the specifications for
each component and the specifications necessary to ensure the identity, strength, quality, purity,
potency, and bioavailability of the drug product (§314.50(d)(1)(ii)(a)). To ensure purity,
applicants should propose and justify appropriate limits on the impurities in their drug substances
and drug product.
A. Refusal to Receive for Lack of Impurities Information
FDA may RTR an ANDA that is not sufficiently complete because it does not on its face contain
information required under §314.94, which includes a demonstration of the purity of the drug
substance and drug product and information on impurities and residues (§§314.101(d)(3),
314.94(a)(9) (requiring ANDA to contain the information required under § 314.50(d)(1)) (see
also Final Rule on Abbreviated New Drug Applications, 57 FR 17950 at 17959 (Apr. 28,
1992)).14
Accordingly, FDA may RTR an ANDA for: (1) failing to provide justification for proposed
limits in drug substances and drug products for specified identified impurities that are above
qualification thresholds; (2) failing to provide justification for proposed limits for specified
unidentified impurities that are above identification thresholds; and (3) proposing limits for
12 At the time of filing, FDA reviews the content of an ANDA to determine, among other things, whether the ANDA
applicant has provided a complete justification for proposed impurity limits. FDA does not conduct a thorough
review of the justification of the proposed impurity limits until after filing, during technical review of the ANDA.
To help applicants ensure the appropriate purity of their drug substance (§314.50(d)(1)(i)) and drug product
(§314.50(d)(1)(ii)(a)), FDA has published the following guidances for industry: ANDAs: Impurities in Drug
Substances; ANDAs: Impurities in Drug Products; and M7 Assessment and Control of DNA Reactive (Mutagenic)
Impurities in Pharmaceuticals to Limit Potential Carcinogenic Risk .
13 Impurities that are monitored in the drug product are classified as degradation products. Process impurities from
the drug substance synthesis are normally controlled during drug substance testing, and therefore are not generally
included in drug product specifications, unless they are also degradation products.
14 “As for possible impurities or residues in the ANDA product, ANDA applicants would be required to provide
information on the drug substance and the drug product as part of the chemistry, manufacturing, and controls section
of the application. This would include information on impurities and residues.” 57 FR 17950 at 17959.

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unspecified impurities (e.g., any unknown impurity) above identification thresholds. FDA
expects applicants to develop and use appropriate analytical methods to detect all observed
impurities. Applicants are encouraged to review the draft guidance for industry ANDA
Submissions – Content and Format of Abbreviated New Drug Applications for more information
on the characterization of impurities for drug substances and drug products.
B. Providing Justification for Impurity Limits
As stated in Section II, to help applicants ensure the appropriate purity of their drug substance
(§314.50(d)(1)(i)) and drug product (§314.50(d)(1)(ii)(a)), FDA has published two guidances for
industry: ANDAs: Impurities in Drug Substances and ANDAs: Impurities in Drug Products.
These guidances provide recommendations on what CMC information applicants should include
regarding the reporting, identification, and qualification of impurities in drug substances and
impurities that are classified as degradation products in drug products. These guidances provide
recommendations for justifying appropriate impurity limits15 in a drug substance or drug
product.16
If a generic product contains specified identified impurities that exceed the qualification
thresholds17 or specified unidentified impurities18 that exceed identification thresholds,19,20,21 the
ANDA should propose impurity limits and include supporting data to demonstrate that:
15 The terms “impurity limit” as used in this guidance and “acceptance criterion” as used in the FDA guidances
referenced above in this paragraph and in note 4 are synonymous.
16 The referenced guidances apply to drug substances and drug products, generally. However, if FDA has issued a
product-specific guidance, the most stringent impurity identification or qualification threshold would apply. For
example, the guidance for industry Nasal Spray and Inhalation Solution Suspension, and Spray Drug Products –
Chemistry, Manufacturing, and Controls Documentation states that unspecified impurities (degradation products) at
levels of 0.1% or greater should be specified. Therefore, for these specific products, the limits for unspecified
impurities (degradation products) should not exceed 0.1%.
17 See guidances for industry Q3A(R) and Q3B(R2). Identification and qualification thresholds should be based on
the maximum daily dose (MDD) of the drug and total daily intake of impurities, which refers to the publicly
available drug product dosage labeling. These thresholds should be reported as a percentage, and percentages
should be based on lowest total daily intake (TDI) of impurities per ICH guidance tables for all impurities.
18 See supra, note 16. When specified unidentified impurities are listed in the specification, FDA recommends that
applicants describe the identification efforts attempted and clearly identify the procedure used and assumptions
made in establishing the level of the impurity. It is important that specified unidentified impurities are referred to by
an appropriate qualitative analytical descriptive label (e.g., unidentified A, unidentified with relative retention of
0.9).
19 See supra, note 16. In some cases, it may be appropriate to decrease the threshold for qualifying impurities. For
example, if there is evidence that an impurity in certain drug classes or therapeutic classes has previously been
associated with adverse reactions in patients, it may be important to establish a lower qualification threshold. When
such circumstances arise, and when these circumstances have not already been contemplated in a product-specific
guidance, these changes will not be evaluated during the filing review but will be addressed during the technical
review of the ANDA.
20 See guidances for industry Q3A(R) and Q3B(R2) for definitions of an identified impurity, identification threshold,
qualification, and qualification threshold.
21 Acceptance criteria for unspecified impurities should not exceed the identification threshold in the guidances for
industry Q3A(R) and Q3B(R2), even in the case when higher acceptance criteria for unspecified (other) impurities
are listed in the U.S. Pharmacopeia (USP) monograph. If the acceptance criteria for unspecified (other) impurities

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(1) the observed impurity levels and proposed impurity limits do not exceed the level
observed in the reference listed drug (RLD) product;22
(2) the impurity is a significant metabolite of the drug substance;23
(3) the observed impurity levels and proposed impurity limits are adequately justified by
the scientific literature;24
or
(4) the observed impurity levels and proposed impurity limits do not exceed the level that
has been adequately evaluated in toxicity studies.25
FDA will RTR an ANDA under §314.101(d)(3) if the ANDA lacks supporting data or
information to justify the proposed limits for specified identified and/or specified unidentified
impurities that exceed qualification thresholds and/or identification thresholds, respectively, as
described above. Also, FDA will RTR an ANDA under §314.101(d)(3) with proposed limits for
unspecified impurities that exceed identification thresholds.
in the USP monograph are lower than the identification threshold in Q3A(R) and Q3B(R2), the acceptance criteria
for unspecified impurities should be set to the USP level.
22 In the event that the RLD is no longer marketed, thereby preventing the ANDA applicant from obtaining samples
to conduct a comparative analysis, an applicant is required to provide a justification of the proposed impurity limits
based on other criteria delineated in this guidance (e.g., metabolite, scientific literature, or toxicity studies) in order
for that ANDA to be received. An applicant that wishes to use an alternative approach is encouraged to submit a
controlled correspondence to determine the acceptability of the approach prior to ANDA submission.
23 The guidances for industry ANDAs: Impurities in Drug Substances and ANDAs: Impurities in Drug Products state
that a significant metabolite of the drug substance is considered qualified. However, if the level of the significant
metabolite impurity is too high, other quality attributes, such as potency, could be significantly affected. In this
case, FDA recommends that the acceptance criterion be set lower than the qualified level.
24 If the applicant relies on published literature, complete and legible copies of each publication should be included
in the ANDA submission.
25The toxicity assessment should also include an evaluation of potentially genotoxic impurities (PGI) that may
include in silico, in vitro and/or in vivo analyses.