ONDANSETRON ABSORPTION IN ADULTS - EFFECT OF DOSAGE FORM, FOOD, AND ANTACIDS

Ondansetron is a competitive serotonin 5-HT3 receptor 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 th e two one-sided t-tests. The tablet and solution formulations were bio equivalent, as confirmed by similarities in mean C-max (26.3 vs 27.7 n g/ml), T-max (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 mal e subjects, the bioavailability of an 8-mg ondansetron tablet administ ered 5 min after a standard meal was slightly but significantly greate r 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 b ioavailability of the ondansetron tablet.