Cilansetron (Pronounced Sil-an-set-ron) is a drug that is a 5HT-3 antagonist currently under trial phase in the EU and US it is manufactured by Solvay Pharmaceuticals INC. 5HT-3 receptors are responsible for causing many things from nausea to excess bowel movements. It is thought in conditions like IBS the receptors have become faulty or oversensitive. 5HT-3 antagonists work by blocking the nervous and chemical signals from reaching these receptors. Studies have shown that the drug can greatly improve quality of life in men and women with diahorrea predominant IBS Cilansetron is the first 5HT antagonist specifically designed for IBS that is effective in men as well as women. Solvay has had considerable difficulty with the medicines regualtors in the UK, EU and USA with regards to licensing the drug. This could possibly be due to the problems discovered after licensing with the drug Lonotrex. At time of writing; Solvay had recently withdrawn its application to the FDA but was continuing its talks with the MHRA in the UK and EU regulators. It is not currently known what sort of timeframe the public are looking at to be able to obtain the drug. This matter is not helped by the lack of information about cilansetron and its trials in the public domain. The regulators have also stated this in their responses. There is no information about future trials currently available. Some people have tried the Anti-enemtic ondansetron HCI (Zofran) as a substitute for the time being, results are mixed but noted effect has been shown some male and females However; due to its license in the UK it is usually only prescribable at consultant level. Since the licensing of a generic version it is more likely an NHS prescription will be accepted as the branded version is very expensive (Official NHS pricing.) In the USA and Canada: availability often depends on insurance and the doctors personal opinion on off-label prescribing.