Effects of food on oxaprozin bioavailability

Twelve healthy volunteers received single 1200-mg oral doses of oxaprozin while fasting and immediately after a standard breakfast in a two-period crossover design with three weeks between administrations. Oxaprozin plasma concentrations were monitored during a 10-day period after each dose. No statistically significant differences were noted between kinetic parameters obtained in the fasting and post-prandial states for mean peak plasma concentrations (Cmax, 103 vs. 109 micrograms/ml), absorption rate constants (ka, 1.1 vs. 0.8 h-1), or total AUC (7042 vs. 7066 micrograms/ml X hr). Compared with doses administered during fasting, postprandial doses led to a delay in the onset of absorption in the gastrointestinal tract (lag time t0, 24 vs. 9 min), but not in the peak time (tmax approximately 5 hours). Oxaprozin's mean residence time t was slightly shorter for subjects in the postprandial state (72 hours) than for those in fasting state (73 hours), probably because of the intrasubject variability in half-life (48 vs. 50 hours). The results of this study indicate that the ingestion of food has no effect on the bioavailability of oxaprozin.