Abstract: Aim The two-crossover trial was employed to compare the pharmacokinetics and bioavail-ability of naproxen sustained release capsule (SRC)with that of the standard tablet (ST)in healthy volunteers.Methods In single dose study, each of 10 volunteers received 500 mg naproxen in either of the two forms and in steady state study, 8 volunteers each received either 500 mg- SRC once daily (250 mg b.i.d.).The serum naproxen concentrations were deter-mined by a HPLC method.Results After single dose of the two forms, the area under curve (AUC)values of the the two forms were similar or equivalent.The peak concentrations (C_max)and peak time (T_peak)of two forms were different, the C_max and T_peak of SRC were 85.5 ug/ml and 6.0h, respectively;the C_max and T_peak of ST were 140.4μg/ml and 3.2h,respectively.In steady-state study, The steady state was achieved on day 3.At steady state, the C_max, C_max/C_min ratios and degree of peak-trough fluctuation (DF)during SRC administration were lower than those during ST administration.Conclusion The naproxen SRC showed its sustained release effect, therefore, it should provide patients with a convenient, efficacious dosage form of naproxen that maintains therapeutic naproxen levels in blood.

Key words: naproxen, sustained release capsule, pharmacokinetics, bioavailability, bioequiv-alence