Ondansetron Absorption in Adults: Effect of Dosage Form, Food, and Antacids

Ondansetron is a competitive serotonin 5‐HT3receptor blocker that has proved useful in the prevention of emesis due to cisplatin and other cancer chemotherapeutic agents. In a randomized, open‐label, crossover study in 24 healthy male subjects, the relative bioavailability of a single 8‐mg tablet was compared with that of an 8‐mg solution using the two one‐sidedt‐tests. The tablet and solution formulations were bioequivalent, as confirmed by similarities in meanCmax(26.3 vs 27.7 ng/mL),Tmax(1.79 vs 1.70 h), and AUC (166.0 vs 167.3 ng‐h/mL) values. In another randomized, open‐label, crossover study in 12 healthy male subjects, the bioavailability of an 8‐mg ondansetron tablet administered 5 min after a standard meal was slightly but significantly greater than in fasted subjects, as indicated by comparative mean AUC values [201.4 ng‐h/mL (fed) vs 172.5 ng‐h/mL (fasted)]. Coadministration of a magnesium hydroxide/aluminum hydroxide antacid did not affect the bioavailability of the ondansetron tablet.