PHARMACIA’s DIPENTUM (OLSALAZINE) IS "APPROVABLE"
Executive Summary
PHARMACIA's DIPENTUM (OLSALAZINE) IS "APPROVABLE" on May 4. The company is seeking approval of the second-generation sulfasalazine (5-ASA) product for use in the treatment, the maintenance of remission and the prevention of reocurrence of ulcerative colitis. The Dipentum NDA was filed in late 1987. As of July 13, Pharmacia had not yet received final approval for the product. Pharmacia's 25-person U.S. sales force already markets a 5-ASA drug for ulcerative colitis, Azulfidine (sulfasalazine), which has been available since 1941 for the treatment of inflammatory bowel diseases. An NDA for Azulfidine EN-tabs for the treatment of rheumatoid arthritis is pending at FDA. Dipentum cleared FDA's Gastrointestinal Drugs Advisory Committee in September 1988 ("The Pink Sheet" Sept. 19, 1988, T&G-1). The committee voted six to three (with one abstention) in favor of recommending the product's approval for acute treatment of ulcerative colitis, and voted nine to one in favor of the relapse prevention indication. One committee member suggested that Dipentum's primary advantage over other sulfasalazine products is the absence of sulfapyridine, which may cause intolerance to the drug in some patients and reduce sperm counts in some male patients. At the time of the advisory committee meeting, Pharmacia had completed nine controlled studies and four open-label studies (as part of a 21-study clinical program). Nearly 1,400 patients had received olsalazine at that point. Of the nine controlled studies, seven were in acute disease and two were for relapse prevention. Five of the seven acute disease trials compared olsalazine to placebo, while the other two compared olsalazine to sulfasalazine. Committee members expressed concern with the relative efficacy of olsalazine -- due to the small studies of short duration presented by Pharmacia -- and a 36% incidence of diarrhea during clinical trials. One member recommended that olsalazine labeling for acute treatment carry "warnings against diarrhea with introduction of therapy." It was also suggested that approval be granted to Pharmacia on condition that the company conduct a "comprehensive and relative dosing study (to) interpret minimal and maximal dosing." FDA Division of Gastrointestinal and Coagulation Drugs Director Stephen Fredd, MD, agreed that a Phase IV study would help FDA determine the labeling for diarrhea management. Pharmacia said it is currently in discussions "with prominent gastroenterologists and FDA about what the appropriate studies will be after the drug is launched."