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Recently, the U.S. Court of Appeals for the Federal Circuit rewrote the law on patent term extensions. In Pfizer Inc. v. Dr. Reddy’s Laboratories Ltd., the court determined that a patent term extension applies to all salt compounds of the active ingredient covered by the patent, not merely to the specific salt approved by the Food and Drug Administration. The Feb. 27 decision will foreclose efforts by generic drug makers to design new compounds of active ingredients to bypass patent term extensions — and thus to get to market quicker. The 1984 statute commonly known as the Hatch-Waxman Act sought to balance the interests of pioneer pharmaceutical companies, who discover and market new drugs, with those of generic pharmaceutical companies, who sell cheaper copies of those drugs. The act had two general purposes: (1) to increase the availability of lower-priced drugs by expediting generic drug approval, and (2) to encourage new research by extending the patent term to compensate for the time lost while new drugs undergo FDA scrutiny. The patent term extension provisions are located at 35 U.S.C. � 156. Under � 156(a), “[t]he term of a patent which claims a product … shall be extended” if certain criteria are met. The term “product” is defined in � 156(f)(1) as a “drug product.” A “drug product” is defined in � 156(f)(2) as “the active ingredient of a new drug … including any salt or ester of the active ingredient, as a single entity or in combination with another active ingredient.” The Dr. Reddy’s case turned on the statutory interpretation of the definition of “drug product.” SALT VERSUS SALT Pfizer had obtained FDA approval to market the drug Norvasc, generically known as amlodipine besylate. Amlodipine is the active ingredient and besylate is the type of salt used in the drug. After winning FDA approval, Pfizer requested and was granted an extension of a patent covering both the active ingredient and its salt forms. The patent was extended from Feb. 25, 2003, to July 31, 2006. In December 2001, Dr. Reddy’s filed with the FDA a new drug application proposing to market amlodipine as a maleate salt. And Pfizer sued. In the suit, Dr. Reddy’s acknowledged that amlodipine maleate was covered by the original Pfizer patent, but argued that Pfizer’s patent term extension applied only to amlodipine besylate, because that was the product approved by the FDA. In Dr. Reddy’s view, therefore, the original patent expired on Feb. 25, 2003. The District Court agreed, relying in part on Glaxo Operations UK Ltd. v. Quigg (Fed. Cir. 1990). In the earlier case, Glaxo had sought a patent term extension for a patent claiming cefuroxime axetil, an ester compound of cefuroxime. Glaxo marketed cefuroxime axetil as Ceftin. The active ingredient cefuroxime and its salts had been previously claimed in another Glaxo patent, and two cefuroxime salts had been approved by the FDA and marketed as Zinacef and Kefurox. The Patent and Trademark Office denied Glaxo’s application for a patent term extension, concluding that cefuroxime axetil was merely a new form of the already approved cefuroxime, that Ceftin was thus not the “first commercial marketing” of the “drug product” (one of the criteria for extension), and therefore that it was not eligible for a patent term extension. Glaxo sued the PTO and won in District Court. The PTO appealed. On appeal, the Federal Circuit found that cefuroxime axetil, not cefuroxime, was the active ingredient in Ceftin tablets, and therefore held that Glaxo was entitled to the patent term extension. In so ruling, the court soundly rejected the PTO’s argument that Congress intended to limit the definition of “drug product” to “any ‘new chemical entity,’ … which would encompass all acid, salt, or ester forms of a single therapeutically active substance.” DEFINING THE ‘DRUG’ The District Court’s more recent opinion in Dr. Reddy’s was consistent with the Federal Circuit’s decision in Glaxo. Since Glaxo was entitled to a patent term extension for a cefuroxime ester, the “first commercial marketing” of cefuroxime (in salt form) must not have reached other “drug products” containing the same active chemical entity. Applying this logic to the facts in Dr. Reddy’s, the lower court concluded that Pfizer’s patent term extension for amlodipine besylate did not reach Dr. Reddy’s amlodipine maleate. The Federal Circuit disagreed and reversed the lower court’s decision. The appeals court agreed instead with Pfizer’s argument that the term “drug product” includes not only the active ingredient but also any salt or ester of the ingredient. Thus, Pfizer’s patent term extension covered not only its FDA-approved form of amlodipine, i.e., amlodipine besylate, but also Dr. Reddy’s amlodipine maleate. THE MERCK EXTENSION How does one explain the apparent contradiction between Glaxo and Dr. Reddy’s? Perhaps by examining an intervening case, Merck & Co. v. Teva Pharmaceuticals USA Inc. (Fed. Cir. 2003). The Merck case is best known for its holding on patent infringement. However, at the end of the opinion, the court also addressed Teva’s challenge to Merck’s patent term extension, and held that Merck was entitled to the extension. Merck’s drug, Fosamax, is known by the generic name alendronate sodium. Alendronate is the active chemical entity and sodium is the type of salt used in the drug. Merck received FDA approval to market the drug, and also received a term extension for its patent covering the use of the acid form of alendronate for the treatment of osteoporosis. When Teva filed an abbreviated new drug application to sell a generic version of Fosamax, Merck sued in accordance with the Hatch-Waxman provisions. Teva argued that it did not infringe Merck’s patent because it planned to sell alendronate sodium, not the acid form covered by the patent. The Federal Circuit affirmed the lower court’s judgment that alendronate sodium would infringe Merck’s patent. Turning to the patent term extension issue, Teva argued that the extension of Merck’s patent should not have been granted because the patent claim was directed to the acid, while the FDA-approved product was the salt. But the Federal Circuit, quoting from FDA regulations, noted that the term “active ingredient” is defined as “any component that is intended to furnish pharmacological activity.” The court reasoned that Hatch-Waxman and FDA regulations implement the legislative purpose of the act “by providing that the frequent use of salts or esters in a non-therapeutic part of the molecule does not defeat the purposes of the Act.” Thus the court concluded that the administration of the active ingredient in any form “is contemplated in the governing law.” Viewed in light of Merck, the Federal Circuit’s holding in Dr. Reddy’s makes more sense. The court has indicated in numerous opinions that patent term extensions are intended to reward the innovation of the pioneer pharmaceutical company in bringing a new drug to market. In Merck, the court reasoned that in order for the reward to have value, the extension must reach not only the acid form of the active ingredient, but also the salt forms. The holding in Dr. Reddy’s simply extends this rationale to different salt forms of the active ingredient. Whether the apparent conflict between Dr. Reddy’s and Glaxo will be resolved remains to be seen. But clearly, by extending the reach of patent term extensions, the decision in Dr. Reddy’s favors pioneer drug companies over generic drug companies pushing to get to market. Richard J. Berman is a partner in D.C.’s Arent Fox (www.arentfox.com), specializing in the biotechnology and pharmaceutical arts. His practice consists primarily of patent litigation, patent prosecution, and client counseling. He can be reached at [email protected]. If you are interested in submitting an article to law.com, please click here for our submission guidelines.

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