Scilex Pharmaceuticals Inc., Itochu Chemical Frontier Corp., Oishi Koseido Co., Ltd. v. Aveva Drug Delivery Systems, Inc.

N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
SCILEX PHARMACEUTICALS INC., ITOCHU
CHEMICAL FRONTIER CORP., OISHI KOSEIDO
CO., LTD.,
Plaintiffs-Appellants
v.
AVEVA DRUG DELIVERY SYSTEMS, INC.,
Defendant-Appellee
______________________
2025-1002
______________________
Appeal from the United States District Court for the
Southern District of Florida in No. 0:22-cv-61192-WPD,
Judge William P. Dimitrouleas.
______________________
Decided: August 4, 2026
______________________
J ONATHAN D AVIES , Norton Rose Fulbright US LLP,
Washington, DC, argued for plaintiffs-appellants. Also
represented by S ANYA SUKDUANG.
J OSEPH T HOMAS J AROS , Rakoczy Molino Mazzochi
Siwik LLP, Chicago, IL, argued for defendant-appellee.
Also represented by WILLIAM A. RAKOCZY , D YLAN SACENTI,
CONLY S. WYTHERS .
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SCILEX PHARMACEUTICALS INC. v.
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______________________
Before REYNA, MAYER , and HUGHES , Circuit Judges.
P ER CURIAM .
Scilex Pharmaceuticals Inc. (“Scilex”), Itochu Chemical
Frontier Corp. (“Itochu”), and Oishi Koseido Co., Ltd. (“Oi-
shi”) (collectively, the “Scilex plaintiffs”) appeal a final
judgment of non-infringement entered by the United
States District Court for the Southern District of Florida.
For the reasons discussed below, we affirm.
I. BACKGROUND
Scilex is the exclusive licensee of U.S. Patent Nos.
9,283,174 (the “’174 patent”), 9,931,403 (the “’403 patent”),
and 9,925,264 (the “’264 patent”) (collectively the “asserted
patents”).1 The asserted patents are directed to non-aque-
ous lidocaine patch compositions and methods of using
such compositions.2 See ’174 patent, col. 9 ll. 6–13, ’403 pa-
tent, col. 9 ll. 25–31, ’264 patent, col. 9 ll. 19–27. For pur-
poses of this appeal, claims 1 and 4 of the ’174 patent are
representative. They recite:
1. A non-aqueous patch comprising 0.5 to 7
mass % lidocaine and/or its reactant, and a dissolv-
ing agent consisting of an organic acid and a poly-
alcohol, which are contained in a plaster, wherein
the amount of lidocaine and/or its reactant is 0.1 to
1 mg/cm 2 of the plaster, and wherein the proportion
of dissolving agent to lidocaine and/or its reactant
is 0.5 to 5 mass % of dissolving agent relative to 1
mass % of lidocaine and/or its reactant.
1 Itochu and Oishi are the assignees of the as-
serted patents.
2 For ease of reference, we cite only to the claims
and specification of the ’174 patent unless otherwise noted.
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4. The non-aqueous patch according to claim 1,
wherein the dissolving agent consists of isostearic
acid and dipropylene glycol.
’174 patent, col. 9 ll. 6–13, 18–20 (emphases omitted).
In May 2022, Aveva Drug Delivery Systems, Inc.
(“Aveva”) notified the Scilex plaintiffs that it had filed an
Abbreviated New Drug Application (“ANDA”) with the U.S.
Food and Drug Administration seeking approval of a ge-
neric version of ZTlido®, Scilex’s topical lidocaine patch.3
The Scilex plaintiffs then sued Aveva, alleging that its pro-
posed generic formulation would infringe dependent claim
4 of each of the asserted patents.4 They asserted infringe-
ment under the doctrine of equivalents, contending that
the isostearic acid and oleyl alcohol in Aveva’s patch func-
tioned in the same way to achieve the same result as the
claimed two-component dissolving agent consisting of isos-
tearic acid and dipropylene glycol.5 See J.A. 9792–94,
10475–77. Their theory of infringement was premised on
3 ZTlido® is indicated for the relief of pain asso-
ciated with post-herpetic neuralgia. See Scilex Pharms.
Inc. v. Aveva Drug Delivery Sys., Inc., No. 0:22-CV-61192-
WPD, 2024 WL 4473767, at *2 (S.D. Fla. Aug. 27, 2024)
(“District Court Decision”).
4 The Scilex plaintiffs asserted direct infringe-
ment under the doctrine of equivalents of claim 4 of the ’174
and ’403 patents and indirect infringement under the doc-
trine of equivalents of claim 4 of the ’264 patent.
5 At trial, the Scilex plaintiffs conceded that
Aveva’s ANDA product did not literally infringe the as-
serted claims. See District Court Decision, 2024 WL
4473767, at *11. The district court’s analysis was therefore
confined to whether the Scilex plaintiffs could establish in-
fringement under the doctrine of equivalents.
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the argument that the term “dissolving agent” in the as-
serted claims means a solubilizer or co-solubilizer that pre-
vents crystallization of lidocaine by maintaining the
lidocaine in a dissolved state in the plaster. See J.A. 9178,
9756, 9793.
Following a four-day bench trial, the district court held
that the Scilex plaintiffs had not established infringement
by Aveva’s generic product. The court determined that, in
view of the prosecution history, the “dissolving agent” in
the claimed non-aqueous patch had to both “dissolve[] the
lidocaine and prevent[] crystallization of lidocaine.” Dis-
trict Court Decision, 2024 WL 4473767, at *10. The court
stated that Aveva’s patch “use[d] only a single solvent, n-
heptane, to dissolve the lidocaine,” id. at *12, and that “[n]-
heptane, either alone or in combination with any other
component, [was] not equivalent to any claimed ‘dissolving
agent,’” id. at *13. The court further determined that pros-
ecution history estoppel and the doctrine of claim vitiation
barred the Scilex plaintiffs from asserting that isostearic
acid and oleyl alcohol are equivalent to the claimed two-
component dissolving agent. Id. at *12–16.
This appeal followed. We have jurisdiction under 28
U.S.C. § 1295(a)(1).
II. D ISCUSSION
A.
We review a judgment entered by a district court fol-
lowing a bench trial for both legal error and clearly errone-
ous factual findings. Azurity Pharms., Inc. v. Alkem Lab’ys
Ltd., 133 F.4th 1359, 1363 (Fed. Cir. 2025). “Under the
clear-error standard, we defer to the district court’s find-
ings in the absence of a definite and firm conviction that a
mistake has been made.” Par Pharm., Inc. v. Eagle
Pharms., Inc., 44 F.4th 1379, 1383 (Fed. Cir. 2022) (citation
and internal quotation marks omitted).
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“The doctrine of equivalents provides a limited excep-
tion to the principle that claim meaning defines the scope
of the exclusivity right in our patent system.” VLSI Tech.
LLC v. Intel Corp., 87 F.4th 1332, 1341 (Fed. Cir. 2023).
The doctrine “is limitation specific, not focused only on the
claim as a whole” and “asks whether a substitute element
matches the function, way, and result of the claimed ele-
ment, or whether there are only insubstantial differences.”
Galderma Lab’ys, L.P. v. Lupin Inc., 122 F.4th 902, 910
(Fed. Cir. 2024) (citations and internal quotation marks
omitted); see Warner-Jenkinson Co. v. Hilton Davis Chem.
Co., 520 U.S. 17, 40 (1997); Lab’y Corp. of Am. Holdings v.
Qiagen Scis., LLC, 148 F.4th 1350, 1359 (Fed. Cir. 2025).
B.
Resolution of the present appeal turns on the proper
interpretation of the term “dissolving agent” in the claim
limitation requiring “[a] non-aqueous patch comprising . . .
lidocaine . . . and a dissolving agent consisting of an organic
acid and a polyalcohol, which are contained in a plaster.”
’174 patent, col. 9 ll. 6–9. The parties agree that the
claimed “dissolving agent” must prevent crystallization of
the lidocaine by maintaining it in a dissolved state in the
plaster of the patch. See, e.g., J.A. 9758, 10192, 10347–48.
They are at loggerheads, however, regarding whether the
dissolving agent must also dissolve the lidocaine.
According to the Scilex plaintiffs, the asserted “claims
say nothing about how the lidocaine is dissolved during
manufacture or the order in which the lidocaine, dissolving
agent and other components are combined prior to being
incorporated into the plaster of the patch.” Br. of Plaintiffs-
Appellants 27. In essence, they contend that the asserted
claims are directed to a finished patch in which the recited
two-component dissolving agent functions to maintain lido-
caine in a dissolved, i.e., non-crystalline, state, thereby “al-
lowing for effective delivery to the skin.” Id. at 28. In their
view, therefore, the district court erred in concluding that
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a person of ordinary skill in the art “would understand the
claimed ‘dissolving agent’ both dissolves the lidocaine and
prevents crystallization of lidocaine,” District Court Deci-
sion, 2024 WL 4473767, at *10.
We do not find this argument persuasive. As the dis-
trict court correctly determined, “the asserted claims cover
a topical patch where lidocaine is dissolved in a combina-
tion of an organic acid (isostearic acid) and a polyalcohol
(dipropylene glycol).” Id. at *4. When the phrase “dissolv-
ing agent,” ’174 patent, col. 9 l. 7, is interpreted in view of
the specification and prosecution history, it is evident that
the term refers to a substance that both dissolves the lido-
caine and maintains it in a non-crystalline state in the fin-
ished patch. See, e.g., Regeneron Pharms., Inc. v. Mylan
Pharms. Inc., 130 F.4th 1372, 1378–79 (Fed. Cir. 2025)
(emphasizing that “[c]laim terms are generally given their
plain and ordinary meaning, which is the meaning that one
of ordinary skill in the art would ascribe to a term when
read in the context of the claims, specification, and prose-
cution history”).
C.
We turn first to the claim language. Given that the
claimed therapeutic non-aqueous patch is comprised of two
specified components—an active drug substance, lidocaine,
which is a solid at room temperature, see, e.g., J.A. 10206,
and a “dissolving agent,” ’174 patent, col. 9 l. 7—a person
of ordinary skill in the art would presumably infer that the
recited dissolving agent dissolves the lidocaine. See, e.g.,
Invitrogen Corp. v. Biocrest Mfg., L.P., 327 F.3d 1364, 1367
(Fed. Cir. 2003) (explaining that “[c]laim language gener-
ally carries the ordinary meaning of the words in their nor-
mal usage in the field of invention”). Such an
interpretation is confirmed by the specification. See, e.g.,
Actelion Pharms. LTD v. Mylan Pharms. Inc., 85 F.4th
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1167, 1172 (Fed. Cir. 2023) (explaining that the specifica-
tion “is always highly relevant to the claim construction
analysis” (citation and internal quotation marks omitted)).
The specification explains that a problem with prior art
non-aqueous patches was that they “ha[d] poor permeabil-
ity to the skin because the lidocaine [was] not dissolved and
[was] present in a crystalline state.” ’174 patent, col. 1
ll. 43–45. Therefore, in the claimed invention, “a dissolving
agent” and “lidocaine” are “mixed in a plaster” in order to
“produc[e] a non-aqueous patch in which the lidocaine is
completely dissolved.” Id. col. 2 ll. 14–18 (emphasis added).
This language makes clear that the lidocaine and the dis-
solving agent are mixed to produce a non-aqueous patch in
which the lidocaine is dissolved. We reject, therefore, the
Scilex plaintiffs’ assertion that the asserted claims do not
require the dissolving agent to dissolve the lidocaine.
Other portions of the specification buttress the conclu-
sion that the claimed dissolving agent must dissolve, i.e.,
break apart, the lidocaine. See id. col. 2 ll. 52–57 (“The
most effective proportion of dissolving agent and lidocaine
is 0.5 to 5 mass % of dissolving agent relative to 1 mass %
of lidocaine. In this proportion, lidocaine can be stably
mixed in a dissolved state, increasing the release rate of the
lidocaine to the skin, and causing the drug to effectively
permeate into the muscle.” (emphasis added)); see also id.
col. 2 ll. 39–40 (“According to the present invention, a
small amount of lidocaine is efficiently dissolved.” (empha-
sis added)). Notably, moreover, as the district court cor-
rectly recognized, “[t]he asserted patents describe six
examples of the claimed patch,” District Court Decision,
2024 WL 4473767, at *4, and “[a]ll six examples . . . de-
scribe the use of a combination of an organic acid (e.g., isos-
tearic acid) and a polyalcohol (e.g., dipropylene glycol) to
dissolve [the] solid lidocaine drug substance before mixing
[it] with adhesives to obtain a ‘plaster solution,’” id. at *5.
See ’174 patent, col. 4 l. 6–col. 7 l. 36.
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Although this court has “cautioned against limiting the
claimed invention to preferred embodiments or specific ex-
amples in the specification,” Teleflex, Inc. v. Ficosa N. Am.
Corp., 299 F.3d 1313, 1328 (Fed. Cir. 2002) (citation and
internal quotation marks omitted), we have also recognized
that disclosed embodiments and examples “can shed light
on the intended scope of the claims,” Astrazeneca AB, Ak-
tiebolaget Hassle, KBI-E, Inc. v. Mut. Pharm. Co., 384 F.3d
1333, 1340 (Fed. Cir. 2004). Here, the fact that all six ex-
amples in the specification describe using the “dissolving
agent” combination of an organic acid and a polyalcohol to
dissolve the lidocaine bolsters the conclusion that the
claimed dissolving agent must dissolve the lidocaine and
not simply prevent crystallization of the lidocaine in the
finished patch. See, e.g., In re Power Integrations, Inc.,
884 F.3d 1370, 1377 (Fed. Cir. 2018) (concluding that the
claims at issue could not “be stretched to cover a system in
which a memory separates the counter and the digital to
analog converter and severs the requisite control relation-
ship between them” where “every embodiment disclosed in
the [specification] show[ed] a counter that passes voltage,
current, or control signals to the digital to analog con-
verter”); Astrazeneca, 384 F.3d at 1341 (stating that “[t]he
fact that all of the solubilizers listed in the specification
and used in the working examples were surfactants adds
further support to the conclusion that the term ‘solubilizer’
in the claims should be limited, according to the definition
employed in the specification, to surfactants”). It is nota-
ble, moreover, that the specification identifies no substance
or substances—other than the claimed dissolving agent
consisting of an organic acid and a polyalcohol—that can
appropriately be employed to dissolve the lidocaine in the
claimed patch.
D.
To the extent there remains any uncertainty regarding
the meaning of the term “dissolving agent,” it is dispelled
by reference to statements made by the applicant during
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prosecution. See Personalized Media Commc’ns, LLC v.
Apple Inc., 952 F.3d 1336, 1340 (Fed. Cir. 2020) (explaining
that “[t]he prosecution history . . . may be critical in inter-
preting disputed claim terms because it contains the com-
plete record of all the proceedings before the Patent and
Trademark Office, including any express representations
made by the applicant regarding the scope of the claims”
(citations and internal quotation marks omitted)). During
prosecution of the ’174 patent, the examiner rejected the
original claims over two prior art references, see J.A. 6214–
20, 6433–43, 10199, including U.S. Patent Application
Publication No. 2011/0152377 A1 (“Hanma”), J.A. 6409–
32, which describes patches containing lidocaine, an or-
ganic acid, and a polyalcohol, J.A. 6417–21, and further de-
scribes dissolving lidocaine in an ester solvent and/or a
polyalcohol solvent, J.A. 6421, 6429–32. In response, Oi-
shi, the applicant, stated, at least three different times,
that in the claimed invention the “lidocaine is dissolved in
an organic acid and a polyalcohol,” i.e., in the claimed dis-
solving agent. J.A. 6242–43 (emphasis added); see also
J.A. 6244 (“In the present invention, the lidocaine is simply
dissolved in the organic acid and a polyalcohol.” (emphasis
added)). Because Oishi repeatedly and unambiguously
represented that the lidocaine was dissolved “in” the
claimed dissolving agent, the district court correctly re-
jected the argument by the Scilex plaintiffs that the
claimed dissolving agent need not function to dissolve the
lidocaine. See District Court Decision, 2024 WL 4473767,
at *10.
On appeal, the Scilex plaintiffs argue that during pros-
ecution “the patentees distinguished the claimed invention
from Hanma on the basis that in Hanma, the lidocaine is
reacted with an organic acid to form a salt, as opposed to
simply dissolving the lidocaine, which does not involve a
chemical reaction.” Br. of Plaintiffs-Appellants 53–54 (em-
phases omitted). They assert, moreover, that the prosecu-
tion history does not show that “the patentees clearly and
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unmistakably distinguish[ed] the claimed invention from
Hanma on the basis of the order in which the components
of the invention are combined or suggest that lidocaine
must be dissolved in the dissolving agent alone prior to
combination with other components of the patch.” Id. at 54
(emphasis omitted). As we have previously made clear,
however, statements made during prosecution can “inform
. . . claim construction” even where such “statements do not
rise to the level of unmistakable disavowal.” Shire Dev.,
LLC v. Watson Pharm., Inc., 787 F.3d 1359, 1366 (Fed. Cir.
2015). Accordingly, even assuming, arguendo, that Oishi’s
repeated and consistent statements that the lidocaine is
dissolved in the claimed dissolving agent are insufficient to
give rise to disclaimer, they nonetheless provide cogent ev-
idence supporting the conclusion that the claimed dissolv-
ing agent functions to dissolve the lidocaine. See
Personalized Media Commc’ns, 952 F.3d at 1340 (explain-
ing that even where prosecution history evidence does not
rise to the level of disclaimer, “an applicant’s repeated and
consistent remarks during prosecution can define a claim
term by demonstrating how the inventor understood the
invention”).
E.
In sum, we conclude that, in view of the specification
and prosecution history, the district court correctly deter-
mined that the claimed “dissolving agent,” ’174 patent,
col. 9 l. 7, must dissolve the lidocaine as well as maintain
it in a non-crystalline state in the finished patch. The
Scilex plaintiffs do not meaningfully dispute that they can-
not show infringement by Aveva’s generic product if this
court affirms the district court’s claim construction of the
term “dissolving agent.” See, e.g., Oral Arg. at 24:17–33.
In this regard, we note that Aveva uses a single solvent, n-
heptane, to dissolve the lidocaine and, as the district court
properly found, “[n]-heptane, either alone or in combina-
tion with any other component, is not equivalent to [the]
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claimed ‘dissolving agent.’” District Court Decision, 2024
WL 4473767, at *13.
Because we conclude that the district court correctly
determined that Aveva’s ANDA product did not infringe
under a proper construction of the term “dissolving agent,”
we need not reach the court’s alternative holdings that:
(1) the Scilex plaintiffs’ “doctrine of equivalents theory that
a mono-alcohol (oleyl alcohol) could be equivalent to the
claimed polyalcohol, dipropylene glycol, would vitiate the
‘polyalcohol’ and ‘dipropylene glycol’ claim limitations,” id.
at *16; and (2) “Oishi clearly and unmistakably disclaimed
use of anything other than a dissolving agent consisting es-
sentially of an organic acid and a polyalcohol,” id. at *14.
We have considered the Scilex plaintiffs’ remaining argu-
ments but do not find them persuasive.
III. CONCLUSION
Accordingly, the judgment of the United States District
Court for the Southern District of Florida is affirmed.
AFFIRMED
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