Apotex Inc. and NovoPharm Ltd. of Toronto filed a courtchallenge against Burroughs Wellcome Inc.'s Canadian patent tothe AIDS drug AZT. The patent gives Burroughs exclusivemarketing rights within Canada until 1998.

Apotex and NovoPharm, which both market generic versions ofpharmaceutical products, claim Burroughs' patent is invalidbecause a National Cancer Institute scientist, not a Burroughs'scientist, discovered AZT's effectiveness against the AIDS virus,according to Apotex spokesman Elie Betito.

Burroughs denies the charge. It "was first to conceive of the useof AZT for treatment of HIV infection," said Burroughs'spokeswoman Kathy Bartlett. "Creative insight" is the basis ofthe U.S. patent for AZT, she said.

Apotex, which sells AZT to the United States through a mailorder company based in the Bahamas, claims it can provide thedrug at two-thirds Burroughs' price. Burroughs charges $1.20per 100 mg tablet. A normal dose is 100 of these tablets amonth, Betito said.

Prior to 1987, Canadian patent law included a "compulsorylicensing mechanism" for pharmaceuticals. This permitted thesale of generic copies of proprietary drugs, Betito said. Makersof generic equivalents paid the patent holder a 4 percentroyalty on sales. Following negotiations on the U.S.-Canada FreeTrade Act, patent holders were given market exclusivity forseven to 10 years. -- Rachel Nowak

(c) 1997 American Health Consultants. All rights reserved.