FDA APPROVAL OF GENERIC VERSIONS OF MAXZIDE BARRED BY TEMPORARY RESTRAIINING ORDER; HEARING ON VITARINE ANDA EXCLUSIVITY GRANT SCHEDULED FOR NOV. 23

FDA cannot approve new ANDAs for generic versions of Mylan's Maxzide until after Nov. 23, the date of a formal court hearing, New York Federal Eastern District Court ruled Nov. 13. The court issued the temporary restraining order in response to a Nov. 10 complaint against FDA filed by American Therapeutics. The Bohemia, New York-based company received approval for the triamterene/hydrochlorothiazide combination product on Nov. 3, but cannot come to market until April 17, 1988, because of 180 days exclusivity granted to another generic company, Vitarine ("The Pink Sheet" Nov. 9, p. 4). Vitarine, which has not yet received FDA approval to market its version of Maxzide, was granted exclusivity for being the first firm to file an ANDA for the antihypertensive and successfully challenge Mylan's patent on the product. The complaint asks the court to revoke the ANDA exclusivity granted to Vitarine and to make American Therapeutic's approval effective immediately. The temporary restraining order prevents FDA from approving Vitarine's ANDA for the product, and thus getting a jump on the market for generic versions of Maxzide, until the court can review the merits of the exclusivity grant. American Therapeutics is also asking the court for a declaration that the provisions of the Waxman/Hatch law on ANDA exclusivity are "unconstitutionally vague and indefinite." The complaint argues that portion of the law should be voided "because it empowers the FDA to enforce the statute in an arbitrary fashion." The filing points out that American Therapeutics, the only company with an approved ANDA for the combination product, is barred from marketing by exclusivity held by another company which cannot come to market because it does not have an approved application. The complaint also argues that although Vitarine met the ANDA exclusivity criteria of successful challenge of a patent held by the innovator company, the Maxzide patent is not the type of patent covered under the exclusivity provisions of the law. "The Mylan patent is a process and product-by-process patent and does not claim the drug or a method of using such drug," the filing states. "The legislative history clearly excludes process and manufacturing patents from being listed patents. The only patents authorized to be included by the legislative history are a product patent and a method of use patent." In support of the argument, the complaint notes that "at least five separate companies which have submitted ANDAs for generic equivalents for Maxzide . . . have been found by Mylan not to infringe the listed patent." In view "of the numerous parties, each of whom has filed an ANDA for the listed drug," the filing continues, "it is arbitrary and capricious for the FDA not to reexamine the listing of the Mylan patent and not to delist the Mylan patent." American Therapeutics also raised the applicability of the ANDA exclusivity provisions to Mylan's formulation patent for Maxzide in an Oct. 1 letter to FDA. The agency responded in its Nov. 3 approval letter to the company that it views patents covering a product and not just a process to be covered by the ANDA exclusivity portion of the ANDA/Patent Restoration law. Vitarine is the first company to obtain ANDA exclusivity for a product since the passage of the ANDA/Patent Restoration law in September 1984. FDA's decision to grant Vitarine exclusivity without an approved ANDA and then subsequently approve American Therapeutic's application -- a situation likely to bring on a lawsuit -- puts interpretation of the complicated ANDA exclusivity provisions of the law in the hands of the court. Barr Labs, another company with an ANDA pending for a generic version of Maxzide, is understood to be considering a law suit on the agency's exclusivity decision.