Comparative bioavailability of a generic and two compounded naproxen sodium suspensions administered to rats.

The purpose of this study was to determine naproxen concentrations in rat plasma samples by HPLC and to compare the bioavailability of a generic and two compounded naproxen sodium suspensions (test 1 and test 2). Analysis was run at a fl ow rate of 1.2 mL.min-1 with a mobile phase of acetonitrile: NaH2PO4 0.01 M pH 4.00 (50:50, v/v) at 280 nm, using a C18 column (150 mm x 4.6 mm, 5 μm). The calibration curve was linear (R2 = 0.9987) over the range of 0.25 - 200 μg.mL-1. The precision for inter and intra-day analysis ranged from 2.46% to 12.39%. Cmax, Tmax and AUCt were 191.25 ± 11.17 μg.mL-1, 1.00 ± 0.106 h and 2438.16 ± 291.34 μg.h.mL-1 for the reference drug, 188.22 ± 24.78 μg.mL-1, 1.06 ± 0.092 h and 1755.02 ± 228.90 μg.h.mL-1 for test 1, and 160.50 ± 10.58 μg.mL-1, 0.66 ± 0.102 h and 1955.28 ± 142.80 μg.h.mL-1 for test 2. No signifi cant differences were found based on analysis of variance, with mean values and 90% CI of test2/reference ratio (Cmax 83.92% and AUCt 80.19%). For test1/reference ratio, the result was Cmax 98.41% and AUCt 71.98%. Based on these results, it can be concluded that the validated method was successfully applied to this study; the test 1 formulation failed to demonstrate a bioequivalence to the reference drug; however, the test 2 and reference naproxen sodium suspension were bioequivalent in terms of the rate and extent of absorption under these conditions.