MERCK's PRILOSEC APPROVED FOR SHORT-TERM DUODENAL ULCER TREATMENT

MERCK's PRILOSEC APPROVED FOR SHORT-TERM DUODENAL ULCER TREATMENT on June 12. The Merck Sharp & Dohme proton pump inhibitor omeprazole (formerly tradenamed Losec) received approval for an additional indication of the "short-term treatment of active duodenal ulcers," according to new labeling. The approved dose for the new indication is 20 mg once a day. "Most patients heal within four weeks," labeling states. "Some patients may require an additional four weeks of therapy." Prilosec "should not be used as a maintenance therapy," labeling states. Merck said June 12 that it is continuing the maintenance therapy studies and will submit the results to FDA. The H[2] antagonists from Merck (Pepcid, famotidine), SmithKline Beecham (Tagamet, cimetidine) and Glaxo (Zantax, ranitidine) all carry the maintenance therapy label. The active ulcer indication is based on results of a multicenter double-blind, placebo-controlled trial of 147 patients. The labeling also includes a foreign, multinational, randomized, double-blind study of 105 patients where 20 mg and 40 mg of Prilosec were compared to 150 mg b.i.d. of ranitidine at two, four and eight weeks. At two and four weeks, omeprazole was statistically superior to ranitidine, but at eight weeks "there was no significant difference between any of the active drugs," labeling states. The new indication approved June 12 appears to represent a compromise between the labeling that had been sought by Merck, the recommendations for usage made by an FDA advisory committee nearly 13 months ago, and FDA concerns about the drug's benefits over other ulcer therapies. Merck was notified by FDA on Dec. 26 that Prilosec was "approvable" for the short-term treatment of active duodenal ulcers poorly responsive to standard treatment. The company noted in a Jan. 11 press release that the "approvable" indication was narrower than that originally recommended by FDA's Gastrointestinal Drugs Advisory Committee in May 1990, and that the company did not accept the narrower indication and was therefore in discussion with FDA over the new labeling ("The Pink Sheet" Jan. 14, In Brief). The advisory committee, which also had looked at omeprazole in March 1989, recommended that omeprazole be approved for use in both acute and refractory duodenal ulcers ("The Pink Sheet" May 28, 1990, p. 3). The committee spent a considerable amount of time at the meeting discussing whether omeprazole offered a unique treatment benefit for refractory ulcers and decided that the drug's benefit for that population was general and not superior to other treatments. Developed by the AB Astra subsidiary AB Hassle, omeprazole has been available in the U.S. since 1989 for the short-term treatment of severe erosive esophagitis, short-term treatment of symptomatic gastroesophageal reflux disease (GERD) poorly responsive to customary medical treatment and long-term treatment of Zollinger- Ellison syndrome. Prilosec has made inroads in the U.S. antiulcer market despite not being indicated specifically for duodenal ulcer treatment. Glaxo made note of the encroachment at a Dec. 3 analysts' meeting where the U.K. company touted the strength of Zantac -- a 49% share of the U.S. in September, a margin of nearly two-to-one over Tagamet -- but noted that the share was down slightly from the 51% share in the previous 12 months. The dip occurred as omeprazole's share of the ulcer market apparently grew in anticipation of the new indication ("The Pink Sheet" Dec. 10, p. 14). Newer figures for Zantac show an approximately 50% U.S. market share through March, the same share as at the end of the year. According to Glaxo numbers presented at the December meeting, Prilosec's market share from its original indications was 5% in September, up from a 2% monthly average share for the year ended June 30, 1990. Franz Humer, senior product development and commercial policies officer at Glaxo Holdings, maintained, however, that Prilosec was gaining share primarily at the expense of Tagamet and Pepcid.