indication

Only for the treatment of symptoms of severe diarrhea-predominant irritable bowel syndrome (IBS) in women with chronic symptoms (generally lasting greater than 6 months) who does not present with anatomic or biochemical GI abnormalities and have not responded to conventional therapy.

pharmacology

Alosetron is a potent and selective antagonist of the serotonin 5-HT₃ receptor type. Activation of these receptors and the resulting neuronal depolarization affects the regulation of visceral pain, colonic transit, and GI secretions processes that are related to IBS. By blocking these receptors, alosetron is able to effectively control IBS.

mechanism of action

Alosetron is a potent and selective 5-HT₃ receptor antagonist. 5-HT₃ receptors are nonselective cation channels that are extensively distributed on enteric neurons in the human gastrointestinal tract, as well as other peripheral and central locations. Activation of these channels and the resulting neuronal depolarization affect the regulation of visceral pain, colonic transit and gastrointestinal secretions, processes that relate to the pathophysiology of irritable bowel syndrome (IBS). 5-HT₃ receptor antagonists such as alosetron inhibit activation of non-selective cation channels which results in the modulation of serotonin-sensitive GI motor and sensory processes.

biotransformation

Hepatic, via microsomal cytochrome P450 (CYP)

absorption

50-60 %

half life

1.5 hours

route of elimination

Renal elimination of unchanged alosetron accounts for only 6% of the dose. Alosetron is extensively metabolized in humans.