5-ht3 antagonist 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. 5-ht3 receptor antagonistdrug classskeletal formula of ondansetron, the prototypical 5-ht3 antagonistclass identifiersusenausea and vomitingatc codea04aabiological target5-ht3 receptorclinical datadrugs.comdrug classesconsumer reportsbest buy drugs