Ondansetron: a novel antiemetic agent.
Ondansetron hydrochloride is a new serotonin receptor antagonist that is effective in preventing emesis associated with cancer chemotherapy. The antiemetic effect appears to be exerted through a peripheral vagal blocking within the gastrointestinal tract, as well as an inhibitory effect within the chemoreceptor trigger zone (CTZ). Plasma concentrations of ondansetron peak 1 hour after an oral dose, and the tablet has an absolute bioavailability of 59%. Ondansetron undergoes extensive hepatic oxidative metabolism in the liver. The half-life of ondansetron is 3.5 hours in healthy volunteers; elderly patients have a slightly reduced clearance, and pediatric patients have increased clearance. Although less than 10% of ondansetron is recovered unchanged in the urine, most metabolites are eliminated by this route. The recommended dose of ondansetron is 0.15 mg/kg for three doses on the day of chemotherapy (30 minutes before chemotherapy and 4 and 8 hours afterward). An alternative regimen includes a single-day dose of 32 mg IV in adult patients before chemotherapy. The efficacy of ondansetron therapy for delayed emesis has not been determined. Ondansetron has proven to be appropriate as a single agent or as an addition to standard antiemetic therapy (ie, corticosteroids, benzodiazepines, neurotransmitter blockers) in preventing and treating acute chemotherapy-induced emesis (CIE). Initial results of clinical trials in prevention of radiotherapy-induced emesis and anesthesia-induced emesis appear positive. Ondansetron is well tolerated, with few adverse events (eg, headache, sedation).
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Drug Development Laboratory, School of Pharmacy, University of North Carolina, Chapel Hill.
Graham
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Hak
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Dukes
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D000970:Antineoplastic Agents / Q000009:adverse effects; D006801:Humans; D017294:Ondansetron / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D014839:Vomiting / Q000139:chemically induced / Q000503:physiopathology
D000970:Antineoplastic Agents; D017294:Ondansetron