Litigation Details for Purdue Pharma L.P. v. Depomed, Inc. (Fed. Cir. 2015)

Purdue Pharma L.P. v. Depomed, Inc. (Fed. Cir. 2015)

Docket		Date Filed	2015-09-15
Court	Court of Appeals for the Federal Circuit	Date Terminated
Cause		Assigned To
Jury Demand		Referred To
Patents	6,340,475; 6,635,280
Link to Docket	External link to docket

Details for Purdue Pharma L.P. v. Depomed, Inc. (Fed. Cir. 2015)

Date Filed	Document No.	Description	Snippet	Link To Document
2015-09-15				External link to document
2015-09-15	25		Proceeding—Ex. 1001) ’475 patent U.S. Patent No. 6,340,475, titled “Extending The … of US Patent No 6,340,475 B2 Ex 1001 “the ’ 475 patent” Paper…2015 IPR2014 00378 Patent 6,340,475 B2 Patent Owner also argues…/2015 IPR2014 00378 Patent 6,340,475 B2 A patent claim is unpatentable… 00378 Patent 6,340,475 B2 these limitations For example as Patent Owner notes	External link to document

Purdue Pharma L.P. v. Depomed, Inc. (Fed. Cir. No. 15-2029): Litigation Summary and Patent Analysis

Last updated: August 3, 2026

Purdue Pharma L.P. v. Depomed, Inc., No. 15-2029, was a Federal Circuit appeal from an inter partes review involving Depomed’s U.S. Patent No. 6,340,475. The Federal Circuit affirmed the Patent Trial and Appeal Board’s decision upholding the challenged patent claims against Purdue’s obviousness attack. The decision was nonprecedential and did not establish a broad new rule on pharmaceutical patentability, but it preserved Depomed’s patent position against Purdue’s invalidity challenge. (Purdue Pharma L.P. v. Depomed, Inc., 643 F. App’x 960 (Fed. Cir. 2016)).

What patents were at issue in Purdue Pharma v. Depomed?

The principal patent was U.S. Patent No. 6,340,475, assigned to Depomed, Inc. The patent concerned controlled-release oral dosage forms designed to provide extended drug release in the gastrointestinal tract.

Item	Detail
Patent	U.S. Patent No. 6,340,475
Patent owner	Depomed, Inc.
Technology	Controlled-release oral dosage forms
Federal Circuit docket	No. 15-2029
Lower tribunal	Patent Trial and Appeal Board
Proceeding	Inter partes review
Federal Circuit decision	March 16, 2016
Citation	643 F. App’x 960
Disposition	PTAB decision affirmed
Primary legal issue	Whether the challenged claims were unpatentable as obvious

The patent claims covered dosage-form architecture involving an active pharmaceutical ingredient and a polymeric matrix. The claimed design addressed sustained release and retention of the dosage form in the gastrointestinal environment. The technology was associated with Depomed’s controlled-release and gastric-retentive drug-delivery platform.

What was the procedural history of the Purdue Pharma and Depomed dispute?

Purdue petitioned for inter partes review of claims in the ’475 patent. The PTAB instituted review and evaluated whether the challenged claims were obvious over the cited prior art.

The Board ultimately rejected Purdue’s invalidity challenge. Purdue appealed to the Federal Circuit, arguing that the PTAB had applied the obviousness standard incorrectly and had not adequately supported its conclusions concerning the prior art, motivation to combine, and expected results.

The Federal Circuit affirmed the PTAB. The court concluded that the Board’s factual findings were supported by substantial evidence and that Purdue had not demonstrated legal error in the Board’s obviousness analysis.

Key procedural timeline

Date	Event
1990s	Depomed’s controlled-release dosage-form technology was developed and patented
2014	Purdue filed an IPR petition challenging claims of the ’475 patent
2015	PTAB issued its final written decision upholding the challenged claims
March 16, 2016	Federal Circuit affirmed in No. 15-2029
2016	Decision became the operative appellate disposition of the IPR challenge

Why did the Federal Circuit uphold Depomed’s patent claims?

The Federal Circuit treated the appeal as a challenge to the PTAB’s factual findings and legal conclusion that Purdue had not established obviousness. The court’s analysis focused on the evidentiary record supporting the claimed combination of structural and functional limitations.

Purdue’s position was that the claimed controlled-release dosage form would have been obvious based on the prior art. The argument depended on combining references that disclosed elements of controlled-release formulations, polymer matrices, drug delivery, and gastrointestinal behavior.

The PTAB found that Purdue had not shown the required combination of:

1. A reason that a skilled person would have modified or combined the references;
2. A reasonable expectation that the resulting dosage form would satisfy the claimed performance characteristics; and
3. Evidence sufficient to establish obviousness for the claims as a whole.

The Federal Circuit did not require the Board to accept Purdue’s proposed combination merely because individual claim elements appeared separately in the prior art. The relevant question was whether the prior art would have led a skilled person to the claimed arrangement with a reasonable expectation of success.

Obviousness findings

The decision illustrates several recurring pharmaceutical patent issues:

• The presence of individual claim elements in separate references does not automatically establish obviousness.
• A petitioner must provide a fact-supported reason to combine or modify the prior art.
• Formulation patents can survive an obviousness challenge when the claimed structure and release behavior depend on an interaction among multiple formulation variables.
• Evidence concerning predictable drug release, dosage-form swelling, erosion, and gastrointestinal retention can determine whether a claimed formulation was reasonably expected to work.

The Federal Circuit’s opinion was short and nonprecedential. It affirmed the PTAB’s determination rather than expanding the governing obviousness doctrine.

What was the legal standard applied in the IPR?

The IPR used the statutory framework in 35 U.S.C. §§ 311-319. Purdue, as the petitioner, bore the burden of proving unpatentability by a preponderance of the evidence. The Board applied the broadest reasonable interpretation standard applicable to the proceeding at the time, subject to the patent’s claim language and specification. (35 U.S.C. § 316(e); 37 C.F.R. § 42.100(b)).

On appeal, the Federal Circuit reviewed:

• Legal conclusions, including claim construction and obviousness, without deference;
• Underlying factual findings, including the scope and content of prior art and motivation to combine, for substantial evidence.

The court’s affirmance indicates that Purdue did not identify reversible error in the Board’s claim analysis or evidentiary findings.

Did Purdue challenge the patent under Paragraph IV?

No. The dispute was an inter partes review proceeding, not a Hatch-Waxman Paragraph IV certification case.

A Paragraph IV challenge arises when a generic applicant certifies that an Orange Book-listed patent is invalid, unenforceable, or not infringed. Purdue’s challenge proceeded through the PTAB under the America Invents Act. The IPR therefore did not itself create an automatic 30-month FDA approval stay under 21 U.S.C. § 355(j)(5)(B)(iii).

The distinction matters commercially. An IPR concerns patent validity in an administrative adjudication. A Paragraph IV case typically involves district-court litigation tied to an abbreviated new drug application, potential approval timing, and generic market entry.

What was the Orange Book status of Depomed’s patent?

The Federal Circuit appeal did not decide whether the ’475 patent was listed in the FDA Orange Book for a particular Depomed product, nor did it determine the listing status of any related Depomed patent.

Depomed’s controlled-release portfolio included multiple patents directed to formulation technology and product-specific protection. Orange Book status depends on the relationship between a patent and an approved drug, including whether the patent claims the drug substance, drug product, or an approved method of use under FDA listing rules.

The No. 15-2029 decision should therefore be read as a patent-validity decision concerning the ’475 patent, not as an FDA listing decision.

What products and formulations were commercially relevant?

The patent technology was relevant to controlled-release oral dosage forms and Depomed’s platform-based pharmaceutical products. Depomed’s broader patent estate included formulation patents associated with extended-release delivery and gastric-retentive dosage forms.

The ’475 patent’s commercial significance depended on:

• Whether a marketed product practiced the asserted claims;
• Whether the patent was listed against that product;
• Whether other formulation patents provided overlapping protection;
• Whether the patent term remained active during the relevant launch period; and
• Whether a competing manufacturer could design around the claimed formulation.

The Federal Circuit decision did not make Purdue a licensee of Depomed technology, establish infringement by a Purdue product, or resolve a damages claim.

How strong was Depomed’s patent estate after the decision?

The decision strengthened Depomed’s position against the specific IPR challenge, but it did not establish that every Depomed formulation patent was valid or enforceable.

Strengths

The ’475 patent received a favorable PTAB final written decision and Federal Circuit affirmance. That outcome reduced immediate invalidity risk for the challenged claims. It also increased the cost of a later validity attack based on substantially similar prior-art theories.

The patent covered formulation characteristics that can be difficult to evaluate solely from a product label. Controlled-release performance often depends on polymer selection, matrix behavior, dosage-form dimensions, hydration, erosion, and release kinetics. Those features can create technical barriers to a clean design-around.

Limitations

The Federal Circuit’s opinion was nonprecedential. It did not create a binding rule that gastric-retentive or controlled-release formulation claims are generally nonobvious.

The decision also did not resolve:

• Infringement;
• Claim scope against a specific competing product;
• Patent enforceability;
• Double patenting;
• Written description or enablement;
• Patent-term adjustment;
• Orange Book listing;
• Regulatory exclusivity; or
• Settlement terms.

Patent strength must therefore be assessed claim by claim and product by product.

Did the case involve formulation patents or method-of-use patents?

The central patent was a formulation patent. The litigation did not primarily concern a method-of-use patent or a therapeutic indication patent.

Formulation patents are often more important in generic-entry analysis than the expiration of the active ingredient patent. A generic company may be able to avoid a method-of-use patent through labeling, but avoiding a formulation patent may require a different release mechanism, polymer matrix, dosage-form geometry, or manufacturing process.

The ’475 patent’s relevance was tied to the physical design and release behavior of the dosage form. That makes it technically distinct from:

• Active-ingredient composition patents;
• Salt, polymorph, or crystalline-form patents;
• Treatment-method patents;
• Dose-regimen patents; and
• Manufacturing-process patents.

What generic-entry risks existed after the Federal Circuit decision?

The affirmance reduced, but did not eliminate, generic-entry risk.

A potential generic challenger could still pursue several strategies:

1. Design-around formulation: Develop a dosage form that does not meet one or more structural or functional claim limitations.
2. New prior-art challenge: Present prior art or combinations not considered in the IPR.
3. District-court litigation: Raise invalidity, noninfringement, or unenforceability defenses in a later infringement action.
4. Regulatory pathway: File an ANDA with a Paragraph IV certification if the relevant patent was Orange Book-listed.
5. Post-grant challenge limits: Account for IPR estoppel under 35 U.S.C. § 315(e), which can restrict later reliance on grounds reasonably available during the IPR.

The practical risk depended on patent expiration and the existence of related patents. A single surviving formulation patent could delay entry if it covered the commercial product and was enforceable. Conversely, expiration of the ’475 patent would remove that particular barrier, even if later-expiring patents remained.

Did the case produce a settlement agreement or licensing deal?

The Federal Circuit decision did not report a settlement agreement, license, or commercial resolution between Purdue and Depomed.

The appellate record addressed the PTAB’s patentability decision. It did not establish that Purdue obtained a license to Depomed’s technology or that Depomed granted Purdue a launch date under a settlement.

No revenue-sharing arrangement, authorized-generic agreement, or cross-license was created by the Federal Circuit judgment.

What was the litigation status after the Federal Circuit decision?

The Federal Circuit affirmed the PTAB’s final written decision. The appellate proceeding therefore ended without invalidating the challenged claims.

The decision did not itself determine whether Purdue infringed the ’475 patent. It also did not award damages, issue an injunction, or set a generic launch date.

The principal legal effect was preservation of the challenged Depomed claims against Purdue’s IPR-based obviousness attack.

How does this case compare with a Hatch-Waxman patent challenge?

Issue	Purdue v. Depomed	Hatch-Waxman Paragraph IV litigation
Forum	PTAB, then Federal Circuit	District court, potentially Federal Circuit
Initiating party	Purdue as IPR petitioner	Generic applicant through ANDA certification
Burden	Petitioner proves unpatentability by preponderance	Patent owner generally proves infringement; generic raises defenses
FDA stay	No automatic 30-month stay from the IPR	Possible 30-month stay under the FDCA
Commercial result	Patent claims survived IPR	Can produce injunction, settlement, or launch date
Main issue	Patentability	Infringement and validity tied to drug approval
Regulatory approval	Not directly determined	Directly connected to ANDA approval

Key Takeaways

• Purdue challenged Depomed’s U.S. Patent No. 6,340,475 through inter partes review.
• The PTAB rejected Purdue’s obviousness challenge.
• The Federal Circuit affirmed in No. 15-2029 on March 16, 2016.
• The patent concerned controlled-release oral dosage-form technology.
• The case was not a Paragraph IV litigation and did not determine FDA approval timing.
• The decision did not establish infringement, damages, a license, or a settlement.
• The ruling preserved Depomed’s patent position against the specific IPR grounds presented by Purdue.
• The decision was nonprecedential and had limited value beyond the factual and evidentiary record of the ’475 patent.

FAQs About Purdue Pharma L.P. v. Depomed, Inc.

What patent number was challenged by Purdue in the Depomed IPR?

Purdue challenged claims of U.S. Patent No. 6,340,475, a Depomed patent directed to controlled-release oral dosage forms.

Was Purdue Pharma the patent owner in the case?

No. Purdue was the IPR petitioner. Depomed owned the challenged patent and defended its validity before the PTAB and Federal Circuit.

Did the Federal Circuit invalidate Depomed’s patent?

No. The Federal Circuit affirmed the PTAB decision rejecting Purdue’s invalidity challenge to the challenged claims.

Did Purdue’s case create a generic launch date?

No. The case did not establish a generic launch date because it was an IPR appeal rather than a Hatch-Waxman Paragraph IV action.

Can the decision be used as broad precedent for controlled-release patents?

Only to a limited extent. The Federal Circuit issued a nonprecedential decision that affirmed the PTAB’s findings on the specific patent, prior art, and evidentiary record.

References

1. Purdue Pharma L.P. v. Depomed, Inc., 643 F. App’x 960 (Fed. Cir. 2016).

2. America Invents Act, Pub. L. No. 112-29, 125 Stat. 284 (2011).

3. 35 U.S.C. §§ 311-319.

4. 35 U.S.C. § 316(e).

5. 37 C.F.R. § 42.100(b).

6. Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j)(5)(B)(iii).

7. 35 U.S.C. § 315(e).