Parenteral ondansetron for the treatment of chemotherapy- and radiation-induced nausea and vomiting.

Ondansetron hydrochloride dihydrate is a 5-hydroxytryptamine (5-HT3) antagonist that was recently approved by the Food and Drug Administration for the treatment of chemotherapy-induced emesis. The mechanism of action is thought to be due to competitive inhibition of specific serotonin receptors in the central nervous system and gastrointestinal tract. In clinical trials with cisplatin-induced emesis, ondansetron resulted in complete control of vomiting (0-2 episodes) in 55-87% of patients during the first 24 hours of chemotherapy administration. It was significantly more effective than metoclopramide in comparative trials. Ondansetron is also being investigated for the treatment of radiation- and anesthesia-associated nausea and vomiting. Studies in animals demonstrate potential efficacy in the treatment of anxiety, drug withdrawal, and schizophrenia. The drug is generally well tolerated, with no reported extrapyramidal reactions.