Bioavailability of a new controlled-release oral naproxen formulation given with and without food.

The influence of concomitant food intake on the plasma concentration of naproxen given as a new controlled-release (CR) formulation (750-mg tablet) was investigated in a crossover study design. Twelve healthy volunteers received a single tablet of naproxen on two occasions separated by a 3-week washout period:- after an overnight fast and immediately after a standard meal. Plasma naproxen levels were measured through HPLC at intervals suitable for obtaining concentration-time curves of both regimens in the range 1--48 hours. It was found that average plasma AUC values were 1978.7 mcg.hr/ml in fasting participants and 1778.6 mcg.hr/ml in postprandial participants. The confidence interval computed by Westlake's method indicated equivalence of values. Food decreased the peak plasma concentration of CR naproxen by about 14%, but the confidence interval (+/- 22%) barely exceeded equivalence limits. There were no significant differences between fasting versus postprandial values for the mean absorption time, or plasma absorption and disposition half-lifes. It is concluded that the bioavailability of CR naproxen is not substantially altered by the ingestion of food.