Title: Cilansetron
CAS Registry Number: 120635-74-7
CAS Name: (10R)-5,6,9,10-Tetrahydro-10-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-pyrido[3,2,1-jk]carbazol-11(8H)-one
Additional Names: l-10[(2-methyl-1H-imidazol-1-yl)methyl]-5,6,8,9,10,11-hexahydro-4H-pyrido[3,2,1-jk]carbazol-11-one
Manufacturers' Codes: KC-9946
Molecular Formula: C20H21N3O
Molecular Weight: 319.40
Percent Composition: C 75.21%, H 6.63%, N 13.16%, O 5.01%
Literature References: Serotonin 5-HT3 receptor antagonist. Prepn: H. H. Haeck et al., EP 297651; eidem, US 4939136 (1989, 1990 both to Duphar Int. Res.); I. van Wijngaarden et al., J. Med. Chem. 36, 3693 (1993). Absolute configuration studies: P. G. Jones et al., Acta Crystallogr. E59, o38, o41 (2003). Pharmacology: A. Botella et al., Fundam. Clin. Pharmacol. 12, 619 (1998). Mechanism of action study: K. Hillsley et al., Neurosci. Lett. 278, 137 (2000). Clinical pharmacology: G. Stacher et al., Br. J. Clin. Pharmacol. 49, 429 (2000). Review of development and therapeutic potential: idem, Curr. Opin. Invest. Drugs 2, 1432-1436 (2001); of clinical experience: W. D. Chey, B. D. Cash, Expert Opin. Invest. Drugs 14, 185-193 (2005).
Derivative Type: Hydrochloride
CAS Registry Number: 120635-72-5; 209859-87-0 (monohydrate)
Trademarks: Calmactin (Solvay)
Molecular Formula: C20H21N3O.HCl
Molecular Weight: 355.86
Percent Composition: C 67.50%, H 6.23%, N 11.81%, O 4.50%, Cl 9.96%
Properties: Crystals, mp 226-228°. [a]D5 -5.0° (c = 1.8 in methanol).
Melting point: Crystals, mp 226-228°
Optical Rotation: [a]D5 -5.0° (c = 1.8 in methanol)
Therap-Cat: In treatment of irritable bowel syndrome.
Keywords: Serotonin Receptor Antagonist.
Cilastatin Cilazapril Ciliary Neurotrophic Factor Cilnidipine Cilomilast

Systematic (IUPAC) name
Clinical data
Pregnancy cat. C
Legal status Unlicensed
Routes Oral
Pharmacokinetic data
Bioavailability 87%
Metabolism Hepatic
Half-life 1.6 - 1.9 hours
Excretion Renal
CAS number 120635-74-7 YesY
ATC code A03AE03
PubChem CID 6918107
ChemSpider 5293321 YesY
KEGG D03495 YesY
Chemical data
Formula C20H21N3O 
Mol. mass 319.4 g/mol
 YesY (what is this?)  (verify)

Cilansetron 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 irritable bowel syndrome (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 (1) Cilansetron is the first 5HT antagonist specifically designed for IBS that is effective in men as well as women.(1)

Solvay has had considerable difficulty with the medicines regulators 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 Lotronex. At time of writing; Solvay had recently withdrawn its application to the U.S. Food and Drug Administration (FDA) but was continuing its talks with the MHRA in the UK and EU regulators. (2)

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.[citation needed]

There is no information about future trials currently available.

Some people have tried the Anti-emetic ondansetron HCl (Zofran) as a substitute for the time being, results are mixed but noted effect has been shown in some males and females (3) 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.