Over the past several years, the market for drugs to treat irritable bowel syndrome (IBS) drugs has been brisk. In 2000, Lotronex (alosetron hydrochloride) was introduced to treat diarrhea-predominant IBS in women. That drug was removed from the marketplace due to risks of ischemic colitis, but was reintroduced for use by select patients under strict supervision from qualified physicians. Zelnorm (tegaserod) was approved in 2002 for use in constipation-predominant IBS in women. There are several drugs currently being developed for treatment of IBS symptoms of diarrhea, constipation, and pain.
Renzapride
Renzapride, a new drug being developed by Alizyme, is intended to treat all three forms of IBS (constipation-predominant, diarrhea- predominant and alternating constipation and diarrhea). The new drug has two components which are produced naturally in the body and affect intestinal motility: 5-HT4 and 5-HT3 receptor antagonists. 5-HT4 is the active ingredient in Zelnorm (tegaserod) that helps prevent constipation and 5-HT3 is the component of Lotronex (alosetron hydrochloride) that helps prevent diarrhea. Renzapride has completed Phase IIb of the approval process. Efficacy of the drug was shown in both men and women, but appears to be more prominent in women.Alizyme is currently designing a phase III trial for renzapride in constipation-predominant irritable bowel syndrome in the United States. The multi-center, randomised, double-blind, placebo-controlled, parallel group, pivotal, efficacy study would involve 1700 women over 12 weeks. Alizyme hopes to have results from this study available in early 2007.
Cilansetron
Solvay Pharmaceuticals is developing Calmactin (cilansetron), a selective 5-HT3 receptor drug for use in treating diarrhea-predominant IBS. In the phase II studies of 471 men and women with diarrhea-predominant IBS, the drug was more effective than placebo in resolving symptoms. Commonly reported side effects included constipation and flatulence.A phase III clinical trial of the drug involving 4000 patients was initially reported to have favorable results. However, the United Kingdom’s Medicines and Healthcare products Regulatory Agency (MHRA) and the United State's Food and Drug Administration (FDA) found the drug not approvable. Both agencies are asking for more clinical trials before the drug can be considered for approval. Solvay Pharmaceuticals, which had hoped to have the drug on the market in 2005, is currently examining its options.
