The purpose of this study was to find out whether the bioavailability of a 550 mg naproxen sodium (CAS 22204-53- 1 ) tablet (Sunprox, test) produced by Sunward Pharmaceutical Sdn Bhd was equivalent to that produced by the innovator. The pharmacokinetic parameters assessed in this study were area under the plasma concentration-time curve from time zero to 72 hours (AUC_t), area under the plasma concentration-time curve from time zero to infinity (AUC_inf), the peak plasma concentration of the drug (C_max), time needed to achieve the peak plasma concentration (t_max), and the elimination half life (t_1/2).

This was a randomized, single blind, two-period, cross-over study which included 26 healthy adult male and female subjects under fasting conditions. In each of the two study periods (separated by a washout of one week) single dose of test or reference drug was administered. Blood samples were taken up to 72 h post dose, the plasma was separated and the concentration of naproxen were determined by HPLC-UV method.

In this study, the mean AUC_t, AUC_inf, C_max, and t_½ of naproxen from the test drug were 936.11 μg.h.mL^-1, 977.03μg.h.mL^-1, 76.55 μg/mL, and 15.11 h, respectively. The mean AUC_t, AUC_inf, C_max, and t_½ of naproxen from the reference drug were 969.77 μg.h.mL^-1, 1013.72 μg.h.mL^-1, 75.92 μg/mL, and 15.11 h, respectively. The median t_max of he test drug and reference drug were 3.0 h and 2.0 h, respectively. The geometric mean ratios (90% CI) of the test drug/ reference drug for naproxen were 96.46% (94.30 – 98.66%) for AUC_t, 96.33% (94.03 – 98.69%) for AUC_inf, and
100.37% (95.90 – 105.05%) for C_max.

Based on this study, it can be concluded that the two naproxen sodium tablets (test and drug reference drug) were bioequivalent in term of the rate and extent of absorption.

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