United States Patent 5,273,995: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent 5,273,995, commonly associated with the pharmaceutical composition of atorvastatin calcium, is a pivotal patent in the realm of cholesterol-lowering medications. This patent, held by Pfizer, has been central to several high-profile legal battles and has significant implications for the pharmaceutical industry. Here, we delve into the scope, claims, and the broader patent landscape surrounding this patent.
Patent Overview
Title and Inventor
The patent, titled "[R-(R, R)]-2-(4-fluorophenyl)-β, δ-dihydroxy-5-(1-methylethyl-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrole-1-heptanoic acid, its lactone form and salts thereof," was invented by Dr. Bruce D. Roth, a renowned chemist at Warner-Lambert Company, now part of Pfizer[1][4].
Assignee and Application
The patent was assigned to Warner-Lambert Company, with the application number 07/660,976. It was approved and granted on December 28, 1993[4].
Patent Claims
Types of Claims
The patent includes various types of claims, such as compound claims, use claims, composition claims, and dosage form claims. These claims are designed to protect the specific chemical structure of atorvastatin calcium, its use as a cholesterol-lowering agent, and its formulation in pharmaceutical products[4].
Specific Claims
Claim 6 of the '995 patent is particularly significant, as it has been the subject of several infringement disputes. This claim specifies the chemical structure of atorvastatin calcium and its pharmacologically acceptable salts, ensuring broad protection for the active ingredient in Lipitor®[1][2].
Patent Scope
Chemical Structure
The patent describes a compound with a specific backbone consisting of two rings joined by a bridge. The five-membered ring contains a nitrogen atom and is a "pyrrole" ring, while the six-membered ring contains an oxygen atom and is a "pyran" or "lactone" ring. The substituents on these rings are carefully defined to ensure the compound's efficacy and uniqueness[1].
Enantiomers and Racemates
A key aspect of the patent is the inclusion of various enantiomers and racemates. Pfizer contends that the claims cover not only racemates but also R-trans enantiomers, S-trans enantiomers, and unequal mixtures of these enantiomers. This broad coverage is crucial for protecting the intellectual property of the drug[1].
Patent Expiration and Extensions
Original Expiration Date
The '995 patent was originally set to expire on December 28, 2010. However, Pfizer sought and obtained extensions under various provisions, including the Hatch-Waxman Act, which allows for extensions due to regulatory delays[1][2].
Reissue and Supplementary Protection
In 2009, the '995 patent was reissued in part as U.S. Patent No. 40,667 ('667 patent), which further extended its protection. Additionally, supplementary protection certificates (SPCs) were granted in several countries to extend the patent's life beyond its original expiration date[5].
Patent Landscape and Litigation
Infringement Cases
Pfizer has been involved in several high-profile infringement cases related to the '995 patent. Notably, the cases against Ranbaxy Laboratories and Apotex Inc. highlight the aggressive defense of Pfizer's intellectual property rights. These cases often revolve around the submission of Abbreviated New Drug Applications (ANDAs) by generic manufacturers, which Pfizer alleges infringe on their patents[1][2][5].
Claim Construction Disputes
In the litigation against Ranbaxy, a significant dispute arose over the claim construction of structural formula I. Pfizer argued that the claim was not limited to racemates but also included other enantiomers, while Ranbaxy contended it was limited to racemates. The court's interpretation of these claims was crucial in determining infringement[1].
Impact on the Pharmaceutical Industry
Generic Entry
The expiration of the '995 patent and its extensions has significant implications for the entry of generic versions of atorvastatin calcium into the market. Generic manufacturers like Ranbaxy and Apotex have sought to market their versions of the drug, leading to intense legal battles over patent infringement[2][5].
Innovation and Competition
The broad scope of the '995 patent and its extensions have influenced the balance between innovation and competition in the pharmaceutical industry. While strong patent protection incentivizes innovation, overly broad patents can stifle competition and delay the availability of affordable generic alternatives[3].
Key Takeaways
- Patent Scope: The '995 patent covers a specific chemical structure of atorvastatin calcium, including various enantiomers and racemates.
- Claims: The patent includes compound, use, composition, and dosage form claims to protect the drug's intellectual property.
- Litigation: Pfizer has been involved in several infringement cases to defend its patent rights against generic manufacturers.
- Expiration and Extensions: The patent's original expiration date was extended through reissue and supplementary protection certificates.
- Industry Impact: The patent's scope and litigation have significant implications for the entry of generic drugs and the balance between innovation and competition.
FAQs
What is the main compound protected by U.S. Patent 5,273,995?
The main compound protected is atorvastatin calcium, a cholesterol-lowering agent marketed under the brand name Lipitor®.
Who is the inventor of the '995 patent?
The inventor is Dr. Bruce D. Roth, a chemist at Warner-Lambert Company.
What are the key claims in the '995 patent?
The patent includes claims for the compound itself, its use, composition, and dosage forms.
Why was the '995 patent reissued?
The patent was reissued in part as U.S. Patent No. 40,667 to extend its protection and address any deficiencies or clarifications needed.
What is the significance of the '995 patent in the pharmaceutical industry?
The patent is significant because it protects a highly successful drug, influencing the timing of generic entry and the competitive landscape in the cholesterol-lowering medication market.
Sources
- Pfizer Inc. v. Ranbaxy Laboratories Ltd., 405 F. Supp. 2d 495 (2005)
- Pfizer Inc. v. Ranbaxy Laboratories Ltd., 321 F. Supp. 2d 612 (D. Del.)
- Patent Claims and Patent Scope, SSRN (2016)
- Pharmaceutical drugs covered by patent 5,273,995, DrugPatentWatch
- Pfizer Inc. v. Apotex Inc., 726 F. Supp. 2d 921 (N.D. Ill. 2010)
