PTAB

IPR2016-01412

Amneal Pharmaceuticals LLC v. Purdue Pharma LP

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Pharmaceutical Formulation Containing Gelling Agent
  • Brief Description: The ’376 patent discloses an oral, controlled-release dosage form for opioids, such as oxycodone, designed to deter abuse. The formulation comprises a controlled-release matrix with the opioid and a gelling agent (a combination of polyethylene oxide and hydroxypropylmethylcellulose) that forms a viscous gel when tampered with (e.g., crushed and mixed with liquid), making it difficult to inject or snort.

3. Grounds for Unpatentability

Ground 1: Claims 1-13 and 16-19 are obvious over Palermo in view of Joshi and The Handbook.

  • Prior Art Relied Upon: Palermo (WO 99/32120), Joshi (Application # 2002/0187192), and The Handbook of Pharmaceutical Excipients (The Handbook).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Palermo taught a controlled-release, abuse-deterrent oral dosage form for opioids, including oxycodone, using a matrix with hydroxypropylmethylcellulose (HPMC). Palermo explicitly recognized its abuse-deterrent properties could be improved by adding a gelling agent. Joshi taught that polyethylene oxide (PEO) is a preferred gelling agent for reducing nasal absorption and injectability of drugs, the exact abuse scenarios addressed by the ’376 patent. The Handbook, a standard industry reference, confirmed that both PEO and HPMC were well-known gelling agents with controlled-release properties and provided data showing a POSITA how to achieve a wide range of viscosities, including those claimed, through routine optimization of polymer grade and amount.
    • Motivation to Combine: A POSITA would combine these references for two primary reasons. First, Palermo expressly taught that adding a gelling agent could improve its formulation’s abuse deterrence, directly motivating a search for suitable agents. Second, the publicly known OxyContin abuse crisis provided a strong market-based motivation to develop abuse-deterrent formulations. A POSITA seeking to implement Palermo’s suggestion would have naturally looked to a reference like Joshi, which taught using PEO for the specific purpose of deterring injection and insufflation.
    • Expectation of Success: A POSITA would have a high expectation of success because the combination involved using known polymers (PEO and HPMC) for their known gelling and controlled-release properties to solve a known problem (opioid abuse). The teachings of The Handbook regarding the predictable viscosity of PEO and HPMC solutions would confirm that the desired gelling effect was achievable through routine experimentation.

Ground 2: Claims 1-13 and 16-19 are obvious over Oshlack in view of Joshi, The Handbook, and Doyon.

  • Prior Art Relied Upon: Oshlack (Patent 5,508,042), Joshi (Application # 2002/0187192), The Handbook, and Doyon (Patent 5,283,065).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Oshlack disclosed a controlled-release oral dosage form comprising a matrix of HPMC and oxycodone hydrochloride, providing a therapeutic effect for at least 12 hours. While Oshlack did not explicitly discuss abuse deterrence, the well-established opioid abuse problem would have motivated a POSITA to add such features. As in Ground 1, Joshi provided the teaching of PEO as a preferred gelling agent to combat abuse via injection or snorting. The Handbook again supplied the technical knowledge about achieving target viscosities. Doyon was cited to show that applying a film coat, as required by claim 17, was a conventional and well-known technique for controlled-release tablets.
    • Motivation to Combine: The primary motivation was the widely recognized need to create abuse-deterrent versions of existing opioid formulations like the one taught in Oshlack. A POSITA looking to add abuse-deterrent properties to Oshlack’s HPMC-based formulation would be motivated to incorporate PEO based on Joshi’s teachings. Joshi further motivated the combination by disclosing that gelling polymers could be used “alone or in combination with other gel forming polymers,” suggesting the addition of PEO to Oshlack’s existing HPMC. Doyon provided the motivation to add a film coating for conventional purposes like modifying taste or appearance.
    • Expectation of Success: Success was predictable as it involved adding a known gelling agent (PEO) to a known controlled-release formulation (Oshlack) to achieve the known and desired benefit of abuse deterrence. The properties of the components were well-understood, and The Handbook provided a clear roadmap for achieving the claimed viscosity levels through routine optimization.

4. Key Claim Construction Positions

  • “Gelling Agent In An Effective Amount To Impart A Viscosity”: Petitioner argued this phrase should be construed based on its function of providing abuse deterrence. For claim 1, which requires "at least 10cP," the broadest reasonable interpretation is simply enough gelling agent to meet that minimum numerical threshold. For claims 18 and 19, which recite viscosity "unsuitable for parenteral administration" or "unsuitable to pull into an insulin syringe," Petitioner argued this functionally means a viscosity of at least 10cP, as the patent specification identifies viscosities in this range as being difficult to inject.
  • “Subjected To Tampering”: The petition asserted that based on the specification’s definition of a “tampered dosage form,” this term should be interpreted to mean the dosage form’s physical properties are changed by mechanical, thermal, or chemical means (e.g., crushing, dissolving, heating) to speed the release of the active ingredient.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-13 and 16-19 of the ’376 patent as unpatentable.