BURROUGHS WELLCOME's RETROVIR (AZT) PATENT CHALLENGED BY BARR

BURROUGHS WELLCOME's RETROVIR (AZT) PATENT CHALLENGED BY BARR following the submission of an ANDA for generic zidovudine. Barr announced April 18 that it had filed an ANDA for AZT on March 19 and notified Burroughs Wellcome on April 9 that it would be challenging the AZT patent. Under Waxman/Hatch, Burroughs Wellcome has 40 days to respond to the challenge. Barr's patent challenge comes on the heels of an AZT patent suit filed in D.C. federal court by Public Citizen on March 18 ("The Pink Sheet" March 25, T&G-1) on behalf of two AIDS patients and the People With AIDS Health Group. Barr said its decision to file an ANDA on March 19 was independent of the Public Citizen lawsuit. Public Citizen has asked the court to invalidate Burroughs Wellcome's patent, arguing that the use of AZT as an AIDS therapy was actually discovered by scientists at the National Cancer Institute. The lawsuit contends that AZT could be imported by the PWA Health Group at a lower cost to patients if the AZT patent held by Burroughs Wellcome is invalidated. Barr's major shareholder and Chairman Bernard Sherman is also president of the Canadian generic firm Apotex, which recently challenged Burroughs Wellcome's AZT patent in Canada. Apotex has been exporting AZT to the mail order firm International Pharmacy, which is located in the Bahamas. The Canadian generic company Novopharm also has challenged Burroughs Wellcome's patent. Burroughs Wellcome's patent for use of AZT for the treatment of AIDS expires on Feb. 9, 2005. Barr noted that it cannot predict when it will be able to market the drug "given the unpredictability of how long such a challenge will take, or whether or not it will ultimately succeed." In addition, under the exclusivity provisions of Waxman/Hatch, Retrovir is protected against a zidovudine ANDA approval before March 19, 1992. In its announcement of the patent challenge, Barr played up the potential savings to AIDS patients if a generic version of AZT were to become available. "We would like to see zidovudine become available at the lowest possible price," Barr President Edwin Cohen said in the company release. The release notes that the current annual cost of AZT therapy is $ 3,000 and that 1990 sales of Retrovir were $ 287 mil. Purdue University Pharmaceutical Economics Research Center Director Stephen Schondelmeyer is also quoted in the Barr release. "Many generics enter the market for one-half to two-thirds of the price of the innovator drug," Schondelmeyer said. "I would think that the same kind of savings could be achieved with zidovudine."