Azasetron hydrochloride

Azasetron hydrochloride (Y-25130 hydrochloride) is a potent 5-HT3 receptor antagonist. It selectively and competitively binds 5-HT3 receptors thereby blocking the serotonin binding site. Azasetron is classified as a derivative of benzamide. It has a different chemical structure from other 5-HT3 receptor blockers. The significant difference is found in the pharmacokinetic profiles resulting in a longer duration of action and a higher affinity for the 5-HT3 receptor^1,2. Azasetron has an IC₅₀ value ~4.9x10^-10 M⁴ and half life of 5.4 hours³.

The 5-HT3 receptor subtype is a member of the Cys-loop ligand-gated cation channels which are expressed throughout the central and peripheral nervous systems and mediate a variety of physiological functions⁵.

Azasetron is mostly administered orally and by I.V (60-70%) and excreted in the urine in an unmetabolized form. Orally-administered azasetron is shown to be absorbed and secreted by the saturable transport mechanism in the small intestine, resulting in good bioavailability (approximately 90%)².

5-HT3 receptor antagonists have been established in a number of clinical trials as effective agents in the management and prevention of nausea and vomiting caused by cancer chemotherapy as well as postoperative nausea and emesis after anesthesia and surgery^1,3.