PHARMACIA's DIPENTUM (OLSALAZINE) RECOMMENDED FOR APPROVAL
PHARMACIA's DIPENTUM (OLSALAZINE) RECOMMENDED FOR APPROVAL for acute treatment of ulcerative colitis as well as for maintenance of remission and prevention of recurrence by FDA's Gastrointestinal Drugs Advisory Committee at its Sept. 16 meeting. The committee voted six to three in favor of recommending Dipentum for acute treatment of ulcerative colitis (with one abstention), and nine to one in favor of the relapse prevention indication. "I agree that a consistent drug effect has been demonstrated on relapse studies," panel member Michael Gershon, MD, Columbia University College of Surgeons, said. However, he said he was "unconvinced that any effect has been demonstrated for acute ulcerative colitis." Gershon, like some other panel members, questioned the adequacy of the data supporting acute treatment of ulcerative colitis. Dipentum will be the second 5-ASA or sulfasalazine product for ulcerative colitis on the market. Reid-Rowell's Rowasa (mesalamine) was approved at the end of 1987 ("The Pink Sheet" Jan. 4, p. 6). In support of Dipentum's approval, committee reviewer Steven Hanauer, MD, University of Chicago, said the drug's chief advantage over other sulfasalazine products is that it does not contain sulfapyridine, which is understood to cause some patient intolerance to sulfasalazine as well as to reduce sperm counts in some male patients. Rowasa also does not contain sulfapyridine. In addition, Dipentum is expected to deliver twice the amount of 5-ASA to the colon as sulfasalazine, according to Pharmacia. A drawback to olsalazine therapy is the incidence of diarrhea, which occurred in 36% of patients. Pharmacia's clinical program for Dipentum consists of 21 clinical studies, with nine controlled studies and four open label studies completed. Altogether, almost 1,400 patients have received olsalazine, Pharmacia presenter Graham May, MD, said. The company relied on the nine controlled studies to provide evidence that the drug was safe and effective for both indications. Seven of the nine trials studied olsalazine in acute disease and two in relapse prevention. Five of the seven trials compared olsalazine to placebo, while the other two looked at olsalazine versus sulfasalazine. Total sample sizes for the nine trials ranged from 30 to 105 patients. The five placebo controlled studies used five primary measures for efficacy: blood in the stool, mucus in the stool, stool consistency, number of bowel movements per day, and signoidoscopy analysis. The committee split over recommending approval for acute treatment of ulcerative colitis due to concerns with Pharmacia's efficacy results. In "each of the five controlled studies . . . there was at least one or two parameters, that were significant . . . but, overall, [the studies] are not that significant," Sandor Szabo, MD, PhD, Harvard Medical School, stated. Gershon added that the results "were not consistent from trial to trial." Other members found the data unconvincing because the studies had a small sample size and were of short duration. Hanauer recommended olsalazine for acute treatment of ulcerative colitis "with warnings against diarrhea with introduction of therapy" and with the caveat that Pharmacia conduct a "comprehensive and relative dosing study such that we can 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 in "working this out, so we'd know what the labeling statement" for diarrhea management should be based on.
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