Solvay Pharmaceuticals manufactures the Cilansetron drug and is used for the treatment of Irritable bowel Syndrome (IBS). This drug is a 5HT-3 antagonist currently under trial phase.5HT-3 receptors are responsible for causing things from nausea to excess bowel movements. Cilansetron is a 5HT-3 receptor antagonist with a structure similar to that of ondansetron, however, in animal studies, cilansetron was 10 times more effective than ondansetron and was orally active at a dose 6 times lower than ondansetron. The in-vitro properties of cilansetron are much similar to those of alosetron, another 5HT-3 receptor antagonist. Cilansetron tends to slow the colonic transit and induce firmer stools with a negligible effect on gastric emptying.

Cilansetron administration in healthy subjects significantly increased the area under the pressure curve and number of intestinal contractions, but did not affect the amplitude, duration of contractions, or baseline pressure. This agent has shown a very high affinity for 5HT-3 receptors and a weak affinity for sigma, M-1, muscarinic, and 5HT-4 receptors. Serotonin receptors are extensively located on enteric neurons of the gastrointestinal tract, as well as the other peripheral and central neurons. Activation of these receptors ultimately affects the regulation of visceral pain, gastrointestinal secretions and colonic transit. These changes within the gastrointestinal system all lead to the development of irritable bowel syndrome, and by blocking these receptors, cilansetron is able to control IBS.

Oral cilansetron has been used very effectively at doses of 1, 2, 4, 8, or 16 milligrams three times daily for the treatment of diarrhea-predominant irritable bowel syndrome. Pharmacokinetic data is very much limited. Cilansetron has an elimination half-life of 1.6 to 1.9 hours and peak plasma concentrations are reached 1 to 1.5 hours following oral administration.