5-HT₃ antagonist

The 5-HT₃ antagonists, informally known as "setrons", are a class of drugs that act as receptor antagonists at the 5-HT₃ receptor, a subtype of serotonin receptor found in terminals of the vagus nerve and in certain areas of the brain. With the notable exceptions of alosetron and cilansetron, which are used in the treatment of irritable bowel syndrome, all 5-HT₃ antagonists are antiemetics, used in the prevention and treatment of nausea and vomiting. They are particularly effective in controlling the nausea and vomiting produced by cancer chemotherapy and are considered the gold standard for this purpose.

The 5-HT₃ antagonists may be identified by the suffix -setron, and are classified under code A04AA of the WHO's Anatomical Therapeutic Chemical Classification System.