Comparative in vitro and in vivo bioavailability of naproxen from tablet and caplet formulations

A 500 mg dose of naproxen in a caplet formulation (product A) or a tablet (Naprosyn 500, product B) was administered to 14 fasting healthy subjects on two separate occasions, separated by a 1–2 week washout period in an open, randomized crossover. Blood samples were drawn periodically and plasma naproxen concentrations measured by HPLC. The median time T max to reach peak concentration for product A was shorter than that for product B (1·025 h versus 1·5 h) but A and B were similar with respect to median peak plasma concentration C max (77·9 mg 1 −1 versus 71·4 mg 1 −1 ), and average area AUC 0–∞ under the plasma concentration—time curve (1210·2 mg 1 −1 h versus 1211·0 mg 1 −1 h). In vitro parameters (A versus B) of mean dissolution time MDT (5·03 min versus 15·0 min), and time for 70% dissolution T 70 (6·67 min versus 20·2 min), differed significantly.