  United States Court of Appeals
      for the Federal Circuit
                     ______________________

          PURDUE PHARMA L.P., THE P.F.
          LABORATORIES, INC., PURDUE
         PHARMACEUTICALS L.P., RHODES
               TECHNOLOGIES,
               Plaintiffs-Appellants

                                     v.

                     EPIC PHARMA, LLC,
                           Defendant
                     ______________________

                           2014-1294
                     ______________________

   Appeal from the United States District Court for the
Southern District of New York in No. 1:13-cv-00683-SHS,
Senior Judge Sidney H. Stein.

    ---------------------------------------------------------------------

          PURDUE PHARMA L.P., THE P.F.
          LABORATORIES, INC., PURDUE
         PHARMACEUTICALS L.P., RHODES
               TECHNOLOGIES,
               Plaintiffs-Appellants

                                     v.

 MYLAN PHARMACEUTICALS INC., MYLAN INC.,
            Defendants-Appellees
           _____________________
2                         PURDUE PHARMA L.P.         v. EPIC PHARMA, LLC




                            2014-1296
                      ______________________

   Appeal from the United States District Court for the
Southern District of New York in No. 1:12-cv-02959-SHS,
Senior Judge Sidney H. Stein.

     ---------------------------------------------------------------------

          PURDUE PHARMA L.P., THE P.F.
          LABORATORIES, INC., PURDUE
         PHARMACEUTICALS L.P., RHODES
       TECHNOLOGIES, GRUNENTHAL GMBH,
               Plaintiffs-Appellants

                                      v.

          AMNEAL PHARMACEUTICALS, LLC,
                 Defendant-Appellee
               ______________________

                         2014-1306, -1307
                      ______________________

   Appeals from the United States District Court for the
Southern District of New York in No. 1:11-cv-08153-SHS,
Senior Judge Sidney H. Stein.

     ---------------------------------------------------------------------

    GRUNENTHAL GMBH, PURDUE PHARMA L.P.,
      THE P.F. LABORATORIES, INC., PURDUE
        PHARMACEUTICALS L.P., RHODES
                 TECHNOLOGIES,
                 Plaintiffs-Appellants

                                      v.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                 3




       TEVA PHARMACEUTICALS USA, INC.,
                Defendant-Appellee
              ______________________

              2014-1311, -1312, -1313, -1314
                 ______________________

   Appeals from the United States District Court for the
Southern District of New York in Nos. 1:11-cv-02037-
SHS, 1:12-cv-05083-SHS, Senior Judge Sidney H. Stein.
                ______________________

               Decided: February 1, 2016
                ______________________

    GREGORY A. CASTANIAS, Jones Day, Washington, DC,
argued for all plaintiffs-appellants. Plaintiffs-appellants
Purdue Pharma L.P., The P.F. Laboratories, Inc., Purdue
Pharmaceuticals L.P., Rhodes Technologies also repre-
sented by JENNIFER LORAINE SWIZE; JOHN JOSEPH
NORMILE, JR., New York, NY; ROBERT J. GOLDMAN, Ropes
& Gray LLP, East Palo Alto, CA; SONA DE, CHRISTOPHER
J. HARNETT, New York, NY.

   BASIL J. LEWRIS, Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP, Washington, DC, for plaintiff-
appellant Grunenthal GmbH. Also represented by
JENNIFER HOWE ROSCETTI, ERIN MCGEEHAN SOMMERS;
CHARLES E. LIPSEY, Reston, VA.

   WILLIAM A. RAKOCZY, Rakoczy Molino Mazzochi Siwik
LLP, Chicago, IL, argued for defendants-appellees Mylan
Pharmaceuticals Inc., Mylan Inc. Also represented by
AMY D. BRODY, ERIC R. HUNT, NATASHA L. WHITE.

    BARBARA MULLIN, Akin, Gump, Strauss, Hauer &
Feld, LLP, Philadelphia, PA, argued for defendant-
appellee Amneal Pharmaceuticals, LLC. Also represented
4                    PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



by STEVEN D. MASLOWSKI, MATTHEW A. PEARSON, ANGELA
VERRECCHIO, JASON WEIL; EMILY CURTIS JOHNSON, Wash-
ington, DC; KENNETH E. CROWELL, STUART D. SENDER,
Budd Larner, P.C., Short Hills, NJ.

    MARK DAVID SCHUMAN, Carlson, Caspers, Vanden-
burgh, Lindquist & Schuman, P.A., Minneapolis, MN,
argued for defendant-appellee Teva Pharmaceuticals
USA, Inc. Also represented by M. JEFFER ALI, JENNELL
CHRISTINE BILEK, ALEXANDRA JANE OLSON, CHRISTOPHER
A. PINAHS, SARAH STENSLAND, TODD S. WERNER.

    DONALD E. KNEBEL, Barnes & Thornburg LLP, Indi-
anapolis, IN, for amici curiae Donald E. Knebel, Mark
David Janis. Also represented by MARK DAVID JANIS,
Indiana University Maurer School of Law, Bloomington,
IN.

   BENJAMIN CONRAD BLOCK, Covington & Burling LLP,
Washington, DC, for amicus curiae Center for Lawful
Access and Abuse Deterrence.
                ______________________

    Before PROST, Chief Judge, REYNA, Circuit Judge, and
               STARK, Chief District Judge. ∗
PROST, Chief Judge.
    This appeal arises from consolidated Hatch-Waxman
proceedings involving the reformulated version of the pain
reliever OxyContin®. The Appellants, Purdue Pharma
L.P., The P.F. Laboratories, Inc., Purdue Pharmaceuticals
L.P., and Rhodes Technologies (collectively, “Purdue”) and
Grunenthal GmbH (“Grunenthal”) asserted a number of
claims from multiple different patents against the Appel-


     ∗
         Honorable Leonard P. Stark, Chief District Judge,
United States District Court for the District of Delaware,
sitting by designation.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                  5



lees, Amneal Pharmaceuticals, LLC (“Amneal”), Epic
Pharma, LLC (“Epic”), Mylan Pharmaceuticals Inc. and
Mylan Inc. (collectively, “Mylan”), and Teva Pharmaceuti-
cals USA, Inc. (“Teva”), all of whom have filed Abbreviat-
ed New Drug Applications (“ANDAs”) seeking to sell
generic versions of OxyContin®. The United States
District Court for the Southern District of New York held
a three-week bench trial in the case against Teva, follow-
ing which it held all of the asserted patent claims invalid.
In re OxyContin Antitrust Litig., 994 F. Supp. 2d 367, 377
(S.D.N.Y. 2014) (“District Court Decision”). The court
then entered orders of dismissal in the three remaining
cases against Amneal, Epic, and Mylan based on collat-
eral estoppel. Purdue and Grunenthal appeal the final
judgment in the Teva action, and Purdue also appeals the
orders of dismissal in the three other cases. For the
reasons stated below, we affirm the district court’s rul-
ings.

                        BACKGROUND
     Oxycodone hydrochloride—the active pharmaceutical
ingredient (“API”) in OxyContin®—is an opioid analgesic
used to treat moderate to severe pain. This consolidated
appeal concerns four patents associated with the reformu-
lated version of OxyContin®: U.S. Patent No. 7,674,799
(“’799 patent”), U.S. Patent No. 7,674,800 (“’800 patent”),
U.S. Patent No. 7,683,072 (“’072 patent”) (collectively,
“the low-ABUK patents”), and U.S. Patent No. 8,114,383
patent (“’383 patent”).
                I. The Low-ABUK Patents
    The low-ABUK patents recite an improved formula-
tion of oxycodone hydrochloride. Those patents describe
an oxycodone salt with extremely low levels of a particu-
lar impurity, 14-hydroxycodeinone (“14-hydroxy”), which
belongs to a class of potentially dangerous compounds
known as alpha, beta unsaturated ketones (“ABUKs”).
The prior art method of synthesizing oxycodone hydro-
6                   PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



chloride involved three steps: first, thebaine, a derivative
of the opium poppy, was oxidized to form 14-hydroxy;
second, the 14-hydroxy was converted to oxycodone free
base through hydrogenation; and third, the oxycodone
free base was reacted with hydrochloric acid to form
oxycodone hydrochloride. The end product created by
that process, however, contained high levels of 14-
hydroxy, on the order of 1500 parts per million (“ppm”).
    In January 2004, the U.S. Food and Drug Administra-
tion (“FDA”) became concerned that 14-hydroxy was
potentially toxic and thus mandated that oxycodone
hydrochloride manufacturers either provide evidence that
the 14-hydroxy levels in their formulations were safe or
reduce the amount of 14-hydroxy to less than 10 ppm.
Even before the FDA’s mandate, however, Rhodes Tech-
nologies—a subsidiary of Purdue—had begun researching
methods to reduce 14-hydroxy levels in its oxycodone API.
The scientists initially hypothesized that the 14-hydroxy
present in the final salt was leftover 14-hydroxy that had
not been hydrogenated in the second step. Thus, they
extended the hydrogenation reaction to completion,
confirming that every molecule of 14-hydroxy converted to
oxycodone free base at step two. But the scientists found
that after step three—transforming the oxycodone free
base into oxycodone hydrochloride—the 14-hydroxy had
returned.
    The scientists thus shifted their focus to step three. It
was well known in the art that an impurity, 8,14–
dihydroxy–7,8–dihydrocodeinone (“8,14-dihydroxy”) was
produced as a byproduct of the oxidation of thebaine (step
one). More specifically, it was known that a particular
isomer of 8,14-dihydroxy was formed: 8β, 14–dihydroxy–
7,8–dihydrocodeinone (“8β”). Scientists did not know with
certainty, however, whether 8α, 14–dihydroxy–7,8–
dihydrocodeinone (“8α”)—a diastereomer of 8β—was also
produced during the oxidation step. Purdue scientists
had previously noted the potential existence of 8α, but no
scientific literature discussed that particular isomer.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                7



Through experimentation, the scientists determined that
8α was indeed being produced at step one and, in fact,
was transforming into 14-hydroxy during the acid-
catalyzed dehydration at step three. To remove the 14-
hydroxy from the oxycodone API, the scientists added
another hydrogenation step at the end of step three to
convert the remaining 14-hydroxy into oxycodone free
base. By June 2003, Rhodes’s laboratory could routinely
produce oxycodone API with 14-hydroxy levels less than
10 ppm using the double-hydrogenation process. Purdue
and Rhodes thus sought approval from the FDA and
patent protection for their low-ABUK oxycodone product.
    The low-ABUK patents continue from application No.
11/391,897, known as the “Chapman Application.” The
claims of the Chapman Application have previously been
before us; we authored a non-precedential decision affirm-
ing the Board of Patent Appeals and Interferences’ de-
termination that the Chapman claims were obvious.
Chapman v. Casner, 315 F. App’x 294, 295 (Fed. Cir.
2009) (Rader, CJ., dissenting). In that case, the Board
declared an interference between the Chapman Applica-
tion and U.S. Patent No. 7,153,966 (“Casner”). The
relevant claims in the Chapman Application related to a
method for making oxycodone API using a hydrogenation
step to remove 14-hydroxy, but they did not require that
some of the remaining 14-hydroxy be derived from the 8α
isomer. Id. The Board compared Chapman’s claims to
the prior art and concluded that they were obvious.
Chapman appealed directly to us, and we agreed with the
Board. We reasoned that, because the claims did not
specify the source of the 14-hydroxy, any prior art refer-
ence that disclosed conditions under which either 8α or 8β
converted to 14-hydroxy would render the claim obvious.
Id. at 297. We further noted that the prior art references
did just that—they disclosed the conversion of 8β to 14-
hydroxy under certain conditions. Id. Thus we affirmed
the Board’s decision to reject the Chapman claims as
obvious. Id. at 297–98.
8                   PURDUE PHARMA L.P.    v. EPIC PHARMA, LLC



    Purdue eventually amended the Chapman claims to
include the claims now on appeal. Unlike the claims in
the Chapman Application, the claims at issue here are
product claims instead of process claims, and they explic-
itly recite 8α as the source of at least a portion of the
minimal amounts of 14-hydroxy remaining in the oxyco-
done API. In 2010, the U.S. Patent and Trademark Office
allowed the claims and issued the low-ABUK patents.
                    II. The ’383 Patent
    The ’383 patent covers abuse-resistant formulations.
Original OxyContin® was a popular opioid analgesic
which delivered a large dose of oxycodone over a twelve-
hour period. In the early 2000s, however, reports of
widespread abuse of Original OxyContin® emerged, and
the problem began to garner significant public attention.
Original OxyContin® was susceptible to tampering be-
cause abusers could crush the tablets easily into powder,
which could then be swallowed, snorted, or injected for an
instant opioid “high.” In 2001, Purdue and the FDA
changed the label of Original OxyContin® to warn doctors
about the potential for abusers to tamper with the dosage
form.
    Purdue thus investigated ways to reformulate Oxy-
Contin® to deter abuse. Purdue initially considered,
among other ideas, creating a tablet that would be diffi-
cult to crush and difficult to inject, but those efforts were
unsuccessful. In 2003, Purdue became aware of technolo-
gy developed by Grunenthal that made tablets extremely
hard (in order to prevent crushing) and formed a gel upon
dissolution in water (in order to prevent injecting).
    Grunenthal first began to research abuse resistant
properties for its opioid product, tapentadol. In October
2002, Johnson & Johnson proposed a joint venture with
Grunenthal, using Johnson & Johnson’s osmotically
controlled-release oral delivery system (“OROS”) to deter
abuse. The OROS technology consists of a tablet with an
outer shell that limits the flow of the API from an inner
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                9



core through the use of a “push compartment” in the
tablet. The hard outer shell is composed of high molecu-
lar weight polyethylene oxide (“PEO”), and the “push
compartment” expands to force the API through a hole in
the outer shell. But the tablet could still be easily
crushed with a mortar and pestle, so it was not a worka-
ble solution. Dr. Johannes Bartholomaeus, who was the
head of pharmaceutical development for Grunenthal at
the time, tried to strengthen tapentadol’s dosage form by
making the entire tablet, instead of just the outer shell,
resistant to crushing. Dr. Bartholomaeus thus designed a
formulation that contained a matrix of API and PEO
throughout the tablet. Moreover, Dr. Bartholomaeus’s
experimentation with PEO demonstrated that using both
heat and pressure to form the tablet resulted in a strong-
er solid that resisted breaking by a hammer or by a
mortar and pestle, and withstood a breaking strength test
that exerted 500 N of force.
     After a series of negotiations, Purdue obtained a li-
cense from Grunenthal to use the abuse deterrent tech-
nology of the ’383 patent in its Reformulated OxyContin®
product. Purdue submitted a New Drug Application to
the FDA in November 2007, proposing a Reformulated
OxyContin®, which the FDA approved in April 2010. By
July 2012, Purdue noted reductions in the abuse of Oxy-
Contin® and provided that information to the FDA. On
April 16, 2013, the FDA withdrew its approval for Origi-
nal OxyContin® and stopped accepting ANDAs that
proposed generic versions of it, reasoning that Reformu-
lated OxyContin® was available to provide the same
benefits with lower risks of abuse and misuse. On the
same day, the FDA approved a new label that allowed
Purdue to market Reformulated OxyContin® on the basis
of its abuse deterrent properties.
                 III. Procedural History
    In March 2011, Purdue sued Teva for infringement of
the low-ABUK patents in response to Teva’s filing of an
10                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



ANDA seeking FDA approval to market generic versions
of Reformulated OxyContin®. Between November 2011
and January 2013, Purdue filed similar lawsuits against
Epic, Mylan, and Amneal. In addition, in June 2012,
Grunenthal and Purdue jointly sued Teva for infringe-
ment of the ’383 patent. The two Teva cases were consol-
idated and joined with the Epic, Mylan, and Amneal
cases, along with six actions involving other defendants,
in multi-district litigation for pretrial purposes.
    In September 2013, the district court held a three-
week bench trial in the Teva cases. 1 The district court
found that the asserted claims were infringed by Teva’s
proposed generic product, but it also held that all of the
claims were invalid as anticipated by or obvious over the
prior art. District Court Decision, 994 F. Supp. 2d at 377.
Based on that decision, the district court issued an order
for Purdue to show cause as to why the actions against
Epic, Mylan, and Amneal should not be dismissed under
the doctrine of collateral estoppel. Purdue stated that it
intended to appeal the Teva decision but it agreed that
the district court’s decision regarding the invalidity of the
low-ABUK patents precluded Purdue’s claims for relief
against the other defendants. Accordingly, the district
court dismissed the three remaining actions based on
collateral estoppel.
    Purdue and Grunenthal appeal the final judgment in
the Teva actions and Purdue also appeals the orders of
dismissal in the three other cases. We have jurisdiction
under 28 U.S.C. § 1295(a)(1).




     1  Before the district court, Purdue accused Teva of
infringing claims 3 and 19 of the ’799 patent, claims 30–
34 and 76–79 of the ’800 patent, claims 1, 4, and 5 of the
’072 patent, and claims 1, 2, 5, 7, and 8 of the ’383 patent.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                     11



                         DISCUSSION
    A patent is invalid for anticipation under 35 U.S.C.
§ 102 if a single prior art reference discloses each and
every limitation of the claimed invention. Schering Corp.
v. Geneva Pharm., 339 F.3d 1373, 1377 (Fed. Cir. 2003).
A single prior art reference may anticipate without dis-
closing a feature of the claimed invention if such feature
is necessarily present, or inherent, in that reference. Id.
Anticipation is a question of fact, which we review for
clear error. Atlas Powder Co. v. Ireco, Inc., 190 F.3d 1342,
1346 (Fed. Cir. 1999).
      A patent is invalid for obviousness “if the differences
between the subject matter sought to be patented and the
prior art are such that the subject matter as a whole
would have been obvious at the time the invention was
made to a person having ordinary skill in the art to which
said subject matter pertains.” 35 U.S.C. § 103(a). Obvi-
ousness is a legal conclusion based on underlying facts.
Graham v. John Deere Co., 383 U.S. 1, 17 (1966). We
review the underlying findings of fact for clear error, and
we review de novo the court’s ultimate legal conclusion of
whether the claimed invention would have been obvious.
Novo Nordisk A/S v. Caraco Pharm. Labs., Ltd., 719 F.3d
1346, 1354 (Fed. Cir. 2013). Underlying factual inquiries
include (i) the scope and content of the prior art; (ii) the
differences between the prior art and the claims at issue;
(iii) the level of ordinary skill in the field of the invention;
and (iv) relevant secondary considerations. KSR Int’l Co.
v. Teleflex, Inc., 550 U.S. 398, 406 (2007); Graham, 383
U.S. at 17–18.
          I. Invalidity of the Low-ABUK Patents
    Purdue challenges the district court’s conclusion that
the asserted claims of the low-ABUK patents are invalid
as obvious. Those claims recite an oxycodone API product
12                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



with low ABUK levels. 2 The district court found that the
prior art taught that oxidation of thebaine produced 14-
hydroxy and that it was well known in the art that 14-
hydroxy could be removed using hydrogenation. District
Court Decision, 994 F. Supp. 2d at 395–96. The court
further determined that the discovery of 8α was not
necessary to the claimed invention: a skilled artisan
would recognize that hydrogenation could be used to
remove the remaining 14-hydroxy, regardless of the
source of the 14-hydroxy. Id. at 405–06. Moreover, the
court concluded that the claim limitation requiring that
the remaining 14-hydroxy is at least in part “derived from
8α[]” is a product-by-process limitation and thus immate-
rial in the obviousness determination. Id. at 405. Final-
ly, the district court found that the secondary
considerations did not demonstrate nonobviousness. Id.
at 407. Purdue alleges clear error in a number of the
court’s findings, but none of its arguments are meritori-
ous.
                    A. Discovery of 8α
    First, Purdue contends that the court failed to proper-
ly credit the discovery of 8α as the core of the claimed
inventions. It relies heavily on Eibel Process Co. v. Min-
nesota & Ontario Paper Co., 261 U.S. 45, 68 (1923), for
the proposition that “where an inventor discovers a non-


     2   All of the asserted claims are product claims. The
asserted claims of the ’072 patent are directed to “an
oxycodone hydrochloride active pharmaceutical ingredi-
ent” with low ABUK levels, see, e.g., ’072 patent col. 34 ll.
57–60, while the asserted claims of the ’799 patent are
directed to an “oral dosage form” of low-ABUK oxycodone
hydrochloride, see, e.g., ’799 patent col. 35 ll. 8–15. The
asserted claims of the ’800 patent are product-by-process
claims; they are directed to “[o]xycodone salt prepared
according to [a] process” that yields low ABUK levels.
See, e.g., ’800 patent col. 35 ll. 49–50.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC               13



obvious source of a problem and then applies a remedy in
response, the invention is nonobvious and worthy of a
patent—even if the remedy, standing alone, would gener-
ally appear to be known in the art.” Purdue Br. 40. In
Eibel Process, the invention was a machine that could
make quality paper at high speeds. 261 U.S. at 54. At
the time, paper-making machines could not operate at
high speeds without producing wrinkled paper. Id. Eibel
discovered that the unequal speeds of paper stock and a
wire in the machine produced the wrinkled paper. Thus,
he made a minor modification in the existing paper-
making machines: he increased the pitch (angle) of the
wire so that, through gravity, the paper stock would
travel at substantially the same speed as the wire, and
the paper would not wrinkle. Id. at 57–58, 64–65. The
Supreme Court upheld the validity of Eibel’s patent,
reasoning that the discovery of the problem—unequal
speeds of paper stock and the wire—was nonobvious, and
thus the solution was as well. Id. at 68. Purdue contends
that, similarly here, the discovery of the source of 14-
hydroxy was not obvious, so the solution of hydrogenating
the oxycodone salt must also be nonobvious.
     Purdue’s reliance on Eibel Process is misplaced. Even
if determining the source of 14-hydroxy in the end product
was not obvious, that problem did not need to be solved to
arrive at the claimed invention; thus, Eibel Process does
not apply. As discussed above, the claimed invention in
Eibel Process was a machine that remedied the problem of
wrinkled paper at high-speed printing. But, here, Purdue
did not claim the remedy of the problem of remaining 14-
hydroxy in the oxycodone API—performing a second
hydrogenation step. Instead, it claimed the end product—
an oxycodone API with low ABUK levels. And, as the
district court found, identification of the source of the
remaining 14-hydroxy as being 8α had no effect on the
structure or nature of the low-ABUK oxycodone product.
Because “[o]ne molecule of 14-hydroxy is the same as the
next, whether derived from 8α or 8β,” knowledge of 8α
14                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



“did not make hydrogenation more or less effective as a
technique for converting 14-hydroxy to oxycodone.”
District Court Decision, 994 F. Supp. 2d at 405.

    Purdue also argues that, without knowing that the
14-hydroxy was derived from 8α, a person of ordinary skill
in the art would not know when to conduct the hydro-
genation step or under what conditions to run the hydro-
genation to create low-ABUK oxycodone. Purdue notes
that the prior art references were directed to lowering 14-
hydroxy levels in the oxycodone free base, not the API or
salt. For example, U.S. Patent No. 6,177,567 (“Chiu
reference”) disclosed a method for preparing low-ABUK
free base, but it did not teach how to convert the low-
ABUK free base into low-ABUK salt. In fact, as Purdue
and the district court noted, Chiu completed his method
by adding acetic acid to the free base. In so doing, Chiu
likely converted the latent 8α into 14-hydroxy in the final
product because 8α reacts with the acid to form 14-
hydroxy. But, again, Purdue claimed the end product; it
did not claim a particular method for creating that prod-
uct, such as the use of hydrogenation after the salting
step. In fact, Teva’s generic product would not infringe if
that were the case because the Teva product is not made
by hydrogenating the salt—instead the free base is puri-
fied through two hydrogenation cycles and then is treated
with acid to create the oxycodone salt. Similarly, nothing
in the asserted patents indicates that the hydrogenation
process to remove 14-hydroxy derived from 8α must be
conducted under different conditions from the process
used to remove 14-hydroxy that is derived from 8β. The
issue again comes down to whether it would be obvious to
a person having ordinary skill in the art to use hydro-
genation to remove the excess 14-hydroxy in the oxyco-
done API. One need not know that the 14-hydroxy was
derived from 8α as opposed to 8β to answer that question.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                   15



            B. “Derived from 8α[]” Limitation
    Purdue next argues that, because the asserted claims
require that the remaining 14-hydroxy in the oxycodone
API is derived from 8α and because 8α was not previously
known in the art as being the source of 14-hydroxy, the
claims must be nonobvious. Indeed, Purdue points out
that the reason it added that limitation was because of
our decision in Chapman where we said the claims were
obvious because the claims did not differentiate between
the 8α and 8β. 315 F. App’x at 297. The district court
rejected that argument because it found that the “derived
from 8α[]” limitation was a process limitation and thus
immaterial to the obviousness analysis.
    Purdue says, first, the limitation is not a process limi-
tation, and, second, even if it is, it should not be wholly
disregarded. Again, Purdue’s arguments fail.
    The relevant claim language provides:
    An oral dosage form comprising . . . oxycodone hy-
    drochloride active pharmaceutical ingredient hav-
    ing less than 25 ppm 14-hydroxy[], wherein at
    least a portion of the 14-hydroxy[] is derived from
    8α[] during conversion of oxycodone free base to
    oxycodone hydrochloride[.]
See, e.g., ’799 patent col. 34 l. 65 to col. 35 l. 4 (emphasis
added). We agree with the district court that “derived
from 8α[]” does not describe the structure of 14-hydroxy
and thus is a process limitation. The patent specification
describes methods for detecting and removing 14-hydroxy
without regard to the source. For example, the written
description defines 8,14-dihydroxy as 8α, 8β, or a mixture
of the two and does not indicate any difference in the
resulting 14-hydrodxy depending on the particular isomer
from which it is derived. More specifically, there is no
suggestion in the patents that the hydrogenation process
changes depending on whether the 14-hydroxy is created
by 8α or 8β. Indeed, even Purdue’s expert testified that
16                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



“[t]he structure of the 14-hydroxy that is generated from
8α is the same structure that is generated from 8β.” J.A.
4428. Because the source of the 14-hydroxy has no effect
on its structure or its removal through hydrogenation, the
limitation that it be “derived from 8α[]” cannot be a struc-
tural limitation.
     We also conclude that, because “derived from 8α[]” is a
process limitation, the district court did not err in disre-
garding the limitation in its obviousness analysis. We
have clearly stated that “‘[i]n determining validity of a
product-by-process claim, the focus is on the product and
not the process of making it.’” Greenliant Sys., Inc. v.
Xicor LLC, 692 F.3d 1261, 1268 (Fed. Cir. 2012) (quoting
Amgen Inc. v. F. Hoffman-La Roche Ltd., 580 F.3d 1340,
1369 (Fed. Cir. 2009)). “That is because of the . . . long-
standing rule that an old product is not patentable even if
it is made by a new process.” Id.; see also SmithKline
Beecham Corp. v. Apotex Corp., 439 F.3d 1312, 1317 (Fed.
Cir. 2006) (“It has long been established that one cannot
avoid anticipation by an earlier product disclosure by
claiming . . . the product as produced by a particular
process.”); In re Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985)
(“If the product in a product-by-process claim is the same
as or obvious from a product of the prior art, the claim is
unpatentable even though the prior product was made by
a different process.”).
    Purdue looks to the exception we carved out in
Amgen: “if the process by which a product is made im-
parts ‘structural and functional differences’ distinguishing
the claimed product from the prior art, then those differ-
ences ‘are relevant as evidence of no anticipation’ alt-
hough they ‘are not explicitly part of the claim.’”
Greenliant, 692 F.3d at 1268 (quoting Amgen, 580 F.3d at
1340). As previously discussed, however, the fact that the
14-hydroxy is derived from 8α imparts no structural or
functional differences in the low-ABUK hydrocodone API
as compared to the prior art products. Thus, the court did
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                17



not err in disregarding the process limitation in its obvi-
ousness determination.
              C. Secondary Considerations
     Finally, Purdue contends that the court erroneously
discounted the secondary considerations which it argues
demonstrate nonobviousness.       Purdue first points to
Rhodes’s commercial success; it says that Rhodes became
Purdue’s oxycodone API supplier by marketing the low-
ABUK features of its product to Purdue, which resulted in
almost $71 million in sales in 2010. As the district court
found, however, Rhodes was not successful at marketing
its low-ABUK oxycodone API to any significant customer
other than Purdue, which is its corporate affiliate. The
district court further found that Purdue invested in
Rhodes not because of the low-ABUK features, but be-
cause it could get oxycodone API at a lower cost from its
subsidiary than it could from an unaffiliated manufactur-
er during times of high demand. Purdue does not persua-
sively rebut these findings on appeal. Thus, the district
court did not clearly err in concluding that there was no
nexus between the low-ABUK product of the patents and
the commercial success of Purdue or Rhodes.
    Purdue next argues that the failure of others is shown
by the experience of Teva’s oxycodone API supplier,
Noramco, Inc. (“Noramco”). Purdue claims Noramco was
unable to obtain low ABUK levels until 2007, years after
Purdue discovered 8α, and only then by infringing the
low-ABUK patents. But, as the district court found, there
is no evidence that Noramco tried but failed to create low-
ABUK oxycodone API. Instead, the record showed that
Noramco and the FDA agreed to a timetable for producing
low-ABUK oxycodone API, that Noramco adhered to that
timetable, and that Noramco continued to manufacture
the higher ABUK products during that time. Purdue also
argues that long-felt need was shown because, although
the FDA only made low-ABUK oxycodone API a regulato-
ry requirement in 2003—less than a year before Purdue
18                 PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



commercialized its low-ABUK product—the need for low-
ABUK products was present long before. That does not,
however, change the fact that there was no pressing need
for companies to create a low-ABUK product before the
FDA’s mandate, as they were able to continue to sell their
higher-ABUK products. Thus, the district court did not
clearly err in finding that Purdue failed to prove the
failure of others or long-felt but unaddressed need.
    Finally, Purdue points to the fact that Noramco cred-
ited Purdue and Rhodes with the discovery of 8α and
contends that such recognition shows praise from compet-
itors. But recognition that Rhodes discovered that 8α is a
byproduct of thebaine oxidation does not equal praise for
the invention—the low-ABUK oxycodone API. Purdue
also argues that industry praise is shown because
Noramco copied its process for creating low-ABUK oxyco-
done, but provides no support whatsoever for that argu-
ment. Finally, Purdue contends that the court wholly
ignored evidence showing that Purdue and Rhodes were
surprised over their discovery and solution. But, again,
there was no surprise as to the patented product. Even if
it was unexpected that thebaine oxidation would create
8α, it was not surprising that, after the FDA mandate,
manufacturers would create a low-ABUK oxycodone API
or that they would do so using the known technique of
hydrogenation.
    We find Purdue’s remaining arguments unpersuasive
and conclude that the asserted claims of the low-ABUK
patents are obvious. We thus affirm the district court’s
finding of invalidity as to those claims.
             II. Invalidity of the ’383 Patent
    Purdue and Grunenthal also challenge the district
court’s conclusion that the asserted claims of the ’383
patent are invalid as anticipated, or, in the alternative,
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                19



obvious. 3 The district court concluded that the asserted
claims are anticipated by WO 97/49384, known as the
McGinity reference, which later became U.S. Patent No.
6,488,963. District Court Decision, 994 F. Supp. 2d at
421–26. The McGinity reference discloses the use of hot-
melt extrusion of high molecular weight PEO to create a
controlled-release dosage form for pharmaceuticals. The
district court found that McGinity disclosed opioid formu-
lations and that it inherently disclosed tablets with a
breaking strength in excess of 500 N, as required by the
asserted claims. Alternatively, the district court conclud-
ed that even if the McGinity reference did not anticipate
the ’383 patent, “a person of ordinary skill in the art
would have had sufficient knowledge and motivation to
make the invention claimed by the ’383 patent.” Id. at
426.
    On appeal, Grunenthal contends that the district
court clearly erred in finding that McGinity discloses all
of the limitations of the asserted claims and that the


   3    Claim 1 is the only independent claim of the ’383
patent and recites:
    A thermoformed dosage form comprising:
         i)   one or more active ingredients with
              abuse potential (A) selected from the
              group consisting of opiates and opioids,
         ii) optionally physiologically acceptable aux-
              iliary substances (B),
         iii) at least 60% by weight of polyalkylene
              oxide (C) having a molecular weight of 1–
              15 million according to rheological meas-
              urements, and
         iv) optionally at least one wax (D)
    wherein said dosage form has a breaking strength
    of at least 500 N and wherein the active ingredi-
    ent with abuse potential (A) is present in a con-
    trolled release matrix of component (C).
20                   PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



district court impermissibly combined discrete disclosures
in McGinity to arrive at its anticipation determination.
Grunenthal also asserts a number of grounds of error in
the district court’s obviousness determination.
     A. McGinity’s Disclosure of Opioid Formulations and
                     Breaking Strength
    McGinity discloses a variety of therapeutic com-
pounds to be used in its formulations, including “analge-
sics such as aspirin, acetaminophen, d[i]flunisal and the
like.” J.A. 135074. Grunenthal argues that, because the
only specifically mentioned drugs are non-opioids, McGin-
ity does not describe formulations that contain opioids
such as oxycodone. It invokes the canon of construction
ejusdem generis—which provides that general terms are
construed as referring to things of the same kind as those
specifically mentioned—to argue that the terms “such as”
and “and the like” should be understood as also referring
to other non-opioids. But, as the district court found, the
McGinity reference cannot be read so narrowly. The
McGinity reference explicitly notes the use of its process
with analgesics to treat pain, and the words “such as” and
the residual clause “and the like” demonstrate that the
application discloses a broader group of analgesics than
just those listed. Moreover, the record showed that opi-
oids are a major class of analgesics and that oxycodone
was one of the most widely prescribed analgesics at the
time. The district court also noted that the McGinity
reference is directed to sustained-release dosage forms
and credited expert testimony that the only analgesics on
the market in a sustained-release form at the time were
opioids. 4 The district court’s assessment is persuasive
and not clearly erroneous. 5



      4 Grunenthal says that the record evidence express-
ly contradicts this testimony, as it shows that there were,
in fact, three analgesics on the market in a sustained-
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                21



    Grunenthal next argues that McGinity does not in-
herently disclose the limitation that the dosage forms
have a breaking strength of at least 500 N. According to
the district court,
   The pivotal evidence [with respect to the breaking
   strength limitation] is a series of breaking
   strength tests that Dr. Fernando Muzzio per-
   formed in preparation for this litigation. Muzzio
   thermoformed thousands of tablets according to
   the McGinity Application disclosures. He used a
   variety of chemical compositions, extruder tem-
   peratures, screw speeds, and die diameters. He
   tested a vast number of the resulting tablets, and
   without exception they withstood forces greater
   than 500N. In fact, Muzzio often exerted forces in
   the thousands of Newtons and never had a tablet
   break.



release form at the time and only two of them were opi-
oids. But Grunenthal never made that argument before
the district court—it did not cross-examine the expert on
this point or otherwise take issue with the accuracy of the
expert testimony. In any event, the fact that two of the
three sustained-release drugs on that market at the time
were opioids is persuasive evidence that a skilled artisan
would understand McGinity as describing formulations
that use opioids.
    5   Grunenthal also contends that McGinity does not
disclose the limitation that the active ingredient has
“abuse potential.” ’383 patent col. 22 l. 3. Because we
find that the district court did not err in concluding that
McGinity discloses the use of an opioid as an active ingre-
dient, and because the record clearly demonstrates that
opioids have abuse potential, we similarly find that the
district court did not err in concluding that McGinity
discloses formulations where the active ingredient has
abuse potential.
22                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



District Court Decision, 994 F. Supp. 2d at 423. The
district court credited Dr. Muzzio’s testing and noted that,
“[i]n contrast with [Dr. Muzzio’s] persuasive experimental
evidence, plaintiffs have not put forward any evidence
that any tablet produced according to the McGinity Appli-
cation can ever break when a force of 500N is applied to
the tablet.” Id. The district court thus concluded that the
McGinity reference “inherently discloses a breaking
strength greater than 500N, because the experimental
results indicate unanimously, reliably, clearly, and con-
vincingly that any tablet made according to the McGinity
Application would exhibit this characteristic.” Id. at 424.
     Grunenthal asserts a number of grounds of error,
many of which focus on the adequacy and reliability of Dr.
Muzzio’s testing. For example, Grunenthal argues that
Dr. Muzzio did not provide API release data, photographs
after breaking strength testing, or laboratory notebooks
for his reproductions of the McGinity disclosures. But the
district court rejected that argument, finding that “Muz-
zio has supplemented his own credibility with abundant
documentary support in the form of raw data, photo-
graphs, and force curves” and concluded that Grunen-
thal’s attacks “do not seriously lessen the weight the
Court assigns to Muzzio’s vast empirical results and
credible opinion on the inherency of a 500N breaking
strength.” Id. Similarly, Grunenthal says that Dr. Muz-
zio did not perform a torque test on its reproductions,
which would have shown if the extrusion was being
accurately repeated. Again, however, the district court
found that argument unpersuasive, concluding that
“because torque is not an input or setting in the extrusion
process, the lack of torque data does not affect the relia-
bility of Muzzio’s process as a replication of the McGinity
Application’s process.” Id. The district court credited Dr.
Muzzio with having “recreated the McGinity Application’s
process fairly, accurately, and with no material variation,”
and Grunenthal has shown no clear error in that finding.
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                  23



    Grunenthal also points to specific disclosures in
McGinity which it argues show that the McGinity formu-
lations do not necessarily have the required breaking
strength. First, it notes that McGinity discloses tablets
that can be scored—making them easy to break in half—
or ground, which it contends is the antithesis of high
breaking strength tablets. Next, Grunenthal argues that
McGinity contemplates the use of heat or pressure to
create the disclosed tablets, but notes that tablets with
500 N breaking strength can only be formed using both
heat and pressure. Neither of those disclosures, however,
changes the fact that every tablet made according to
McGinity’s disclosures and tested by Dr. Muzzio had a
breaking strength of over 500 N. And, again, Grunenthal
has not shown clear error in the district court’s crediting
of Dr. Muzzio’s testing results, nor has it provided any
independent testing to rebut Dr. Muzzio’s findings. 6




    6   Moreover, Grunenthal incorrectly characterizes
the McGinity disclosures. Grunenthal relies on one
isolated sentence to support its argument that McGinity
contemplates the use of heat or pressure in its process:
“[A] hot-melt extrudable polymer is one that is . . . capable
of deformation . . . under elevated heat or pressure.” J.A.
135076. But that sentence merely defines the type of
polymer used; it does not say that the extrusion process
requires only heat or pressure and not both. In fact, in
describing the actual hot-melt process, McGinity says it
should be “conducted at an elevated temperature” and
explains that the pharmaceutical mixture should be
“passed through the heated area of the extruder at a
temperature which will melt or soften the PEO.” J.A.
135077. Indeed, Grunenthal’s own expert testified that
hot-melt extrusion requires achieving the “melt flow”
temperature of ninety-eight degrees Celsius for high
molecular weight PEO. J.A. 3845–46.
24                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



     Grunenthal’s last two arguments relate to testing that
Dr. Muzzio did not perform. Grunenthal notes that Dr.
Muzzio only tested formulations with the active ingredi-
ent disclosed in McGinity, chlorpheniramine maleate
(“CPM”), which is an antihistamine, not an opioid. Thus,
Grunenthal says that Dr. Muzzio’s tests only proved that
CPM formulations would have a breaking strength of 500
N or more, not that opioid formulations, as claimed in the
’383 patent, would have such a breaking strength. But,
Dr. Muzzio testified that any tablet made using at least
fifty weight percent PEO and heated above the melting
point of PEO would have a breaking strength above 500
N, regardless of the active ingredient used. J.A. 3462.
The district court did not clearly err in crediting that
testimony.
    Next, Grunenthal argues that Dr. Muzzio did not per-
form any testing to confirm that the tablets he made
according to the McGinity disclosures were controlled-
release formulations. Grunenthal contends that without
this testing, “there is no clear proof that Teva actually
carried out the same process—and made the same tab-
lets—disclosed in McGinity.” Grunenthal Br. 38. That is
incorrect. As stated above, the district court credited Dr.
Muzzio with recreating the McGinity process “fairly,
accurately, and with no material variation.” District
Court Decision, 994 F. Supp. 2d at 424. Grunenthal has
not shown clear error in the district court’s finding and
cannot do so by claiming that Dr. Muzzio did not conduct
an additional test to confirm what the district court
already found—that he properly replicated the McGinity
process. Grunenthal also says that, without testing the
controlled-release properties of the tablets, Teva cannot
prove that the limitation requiring “a controlled release
matrix of [the PEO]” is disclosed by McGinity. That is
also incorrect. Teva did not need to conduct any con-
trolled-release testing because McGinity clearly discloses
PEO formulations with controlled-release properties. For
example, in the “Field of the Invention” section, McGinity
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                25



says, “The invention relates more specifically to formula-
tions which have been prepared by hot melt extrusion of
mixtures containing high molecular weight PEO and a
therapeutic compound for use in controlled-release drug
delivery.” J.A. 135067. Thus, the district court did not
clearly err in concluding that the controlled-release limi-
tation was disclosed in McGinity.
        B. Combination of McGinity Disclosures
    Finally, Grunenthal argues that the district court
erred by using distinct sections of McGinity and reassem-
bling them into an embodiment to find that all of the
limitations were present. See Application of Arkley, 455
F.2d 586, 587 (C.C.P.A. 1972) (noting that an anticipating
reference “must clearly and unequivocally disclose the
claimed compound or direct those skilled in the art to the
compound without any need for picking, choosing, and
combining various disclosures not directly related to each
other by the teachings of the cited reference”). For exam-
ple, Grunenthal points out that the court selected only
“analgesics” from the long list of pharmaceutical catego-
ries that could be used as the active ingredient, and then
further picked oxycodone, which was not even disclosed,
to find anticipation. Moreover, Grunenthal notes that
McGinity teaches that the amount of PEO will vary
depending on various factors and does not consistently
disclose formulations with at least sixty weight percent
PEO, as required by the claims. Thus, Grunenthal argues
that the court impermissibly chose only those examples
that included the claimed amount of PEO to find anticipa-
tion.
    These arguments are without merit. The disclosures
pointed to by the district court are all “directly related”
and thus there is no impermissible picking and choosing.
Arkley, 455 F.2d at 587. For example, in the section
providing a detailed description of the preferred embodi-
ment, McGinity says:
26                  PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC



     [T]he invention provides a hot-melt extrudable
     controlled release pharmaceutical formulation
     comprising an effective amount of a therapeutic
     compound, high molecular weight [PEO] . . . , the
     [PEO]:therapeutic compound ratio being in the
     range from about 99.99:0.01 to about 80:20 % wt.
J.A. 135802. In that single disclosure, McGinity describes
the controlled-release formulation and the use of over
sixty weight percent PEO. It does not specifically say
what therapeutic compound is used, but it provides a list
of the types of therapeutic compounds contemplated.
That list of compounds, although in a distinct section of
the reference, is directly related to the disclosure repro-
duced above. Thus, the district court did not impermissi-
bly combine distinct disclosures in McGinity to arrive at
the claimed invention.
     We conclude that the district court did not clearly err
in finding that the McGinity reference discloses each and
every limitation in the asserted claims of the ’383 patent.
We thus affirm the district court’s anticipation determina-
tion and do not reach the question of obviousness.
                 III. Collateral Estoppel
    In addition to appealing the judgments of invalidity,
Purdue also appeals the dismissal of the Epic, Mylan, and
Amneal actions with respect to the low-ABUK patents.
On appeal from orders of dismissal due to collateral
estoppel, “our role is limited to reviewing the district
court’s application of collateral estoppel, not the correct-
ness of the [underlying] verdict[].” Pharmacia & Upjohn
Co. v. Mylan Pharm., Inc., 170 F.3d 1373, 1380 (Fed. Cir.
1999). Before the district court, Purdue conceded that
collateral estoppel applied to the judgment of invalidity as
to the low-ABUK patents in the Teva case, which preclud-
ed it from obtaining the relief sought in the remaining
actions. Purdue also does not present any persuasive
argument on appeal as to why collateral estoppel should
PURDUE PHARMA L.P.   v. EPIC PHARMA, LLC                 27



not apply. Thus, we affirm the district court’s dismissal of
the remaining actions as barred by collateral estoppel.
                        CONCLUSION
    For the foregoing reasons, we affirm the district
court’s invalidity determinations as to the low-ABUK
patents and the ’383 patent and the district court’s dis-
missal of the Epic, Mylan, and Amneal actions.
                        AFFIRMED
