GLAXO'S ZANTAC PATENT VICTORY WOULD GIVE FIRM NINE YEARS OF EXCLUSIVITY

GLAXO'S ZANTAC PATENT VICTORY WOULD GIVE FIRM NINE YEARS OF EXCLUSIVITY and ample time to develop an over-the-counter version of the anti-ulcer drug before the patent expires in June 2002. The validity of Glaxo's Form 2 patent (number 4,521,431) is the subject of a patent infringement suit filed by Glaxo against Novopharm that is slated to be heard by Judge Boyle in the Elizabeth City, N.C. federal court beginning Aug. 9. If Novopharm's challenge to the Zantac patent is successful, Glaxo's exclusivity for ranitidine would expire in 1995 under a Form 1 U.S. patent granted for Zantac in 1978. Glaxo invented ranitidine in 1976. The Zantac Form 2 patent covers a ranitidine formulation that exhibits more "favorable filtration and drying characteristics" than Form 1 of ranitidine HC1, the company maintained Aug. 3. Form 2, which Glaxo characterized as a "new crystalline form of the hydrochloride salt," was discovered by Glaxo in 1980 and was granted a U.S. patent in 1985. In 1991, Novopharm filed an ANDA for ranitidine, claiming that Glaxo's Form 2 patent was invalid and indicating that it would market ranitidine HC1 in the U.S. after the Form 1 patent expires in December 1995, Glaxo said. Glaxo sued Novopharm for patent infringement, asking the court to uphold the validity of the Form 2 patent. Novopharm will argue against the validity of the Form 2 patent on the grounds that it is not novel, the company said Aug. 6. "This patent challenge is very straightforward," Novopharm declared. "The second patent filed by Glaxo makes the first patent's drug." Glaxo said it "believes it can demonstrate that the Form 2 patent satisfies all the requirements of patentability, including novelty." Secondarily, Novopharm claims the patent is invalid due to inequitable conduct on Glaxo's part and because Glaxo allegedly failed to disclose the best method of manufacturing Form 2. Novopharm alleges that Glaxo is guilty of "inequitable conduct" because it "purposely misled the patent office with false data to obtain" the Form 2 patent. "Inequitable conduct by the patentee is commonly asserted by a defendant in a patent infringement case," Glaxo maintained. "Glaxo denies that any of its actions constitute inequitable conduct." Finally, Novopharm said it will argue "that Glaxo did not include the best method for making ranitidine into tablet form" in its application. Glaxo, however, said it "believes that it has complied with all the formalities relating to best mode in obtaining the Form 2 patent." Glaxo has declared that the Form 2 patent will allow Zantac to remain the top-selling drug in the world through the 1990s. If the patent is upheld, the company would maintain almost 20 years overall exclusivity on ranitidine, which was first introduced in the U.S. in 1983. If Zantac is switched to over-the-counter status, it will be marketed by Warner-Wellcome Consumer Health Products, a recently formed joint venture merging the OTC products of Warner-Lambert and Burroughs Wellcome ("The Tan Sheet" Aug. 2, p. 1). Glaxo predicted that an NDA for the Rx-to-OTC switch of Zantac will be filed with FDA in late 1994. The Glaxo-Novopharm case will provide a high-profile test of the ability of drug companies to use multiple patents to extend exclusivity of a compound. Earlier this summer, Bristol-Myers Squibb's second Buspar patent was deemed "non-novel" by a federal court judge in a case against Danbury. The Zantac trial is expected to last two weeks and the court's decision is anticipated by the end of the year, Glaxo said. "The result of any appeal by either side following the initial decision would probably be available by the end of 1994," the company added. The first challenge to the Zantac patent was initiated in April 1991 by the Canadian firm Genpharm. The Genpharm trial is set for May 1994, Glaxo said.