Single- and multiple-dose pharmacokinetic comparison of a sustained-release tablet and conventional tablets of naproxen in healthy volunteers.

The pharmacokinetics of a new sustained-release tablet of naproxen (500 mg once daily) were compared with a conventional tablet (250 mg twice daily) after single- or multiple-dose oral administration in healthy volunteers using an open, randomized two-way crossover experimental design. Naproxen was well absorbed from the sustained-release tablet (approximately 97%) compared with the conventional tablet. Pharmacokinetic data showed that the sustained-release formulation reached significantly delayed mean peak plasma levels (Cmax) in both single- and multiple-dose studies and lower Cmax in a single-dose study than the conventional formulation. However, there were no statistically significant differences in other pharmacokinetic parameters, including area under the concentration-time curve (AUC), elimination half-life (t1/2), and elimination rate constant (Ke), in either single- or multiple-dose studies between the two treatments. In addition, there were no significant differences between formulations in Cmax, minimum plasma concentration (Cmin), and fluctuation index in the multiple-dose study.