COMPARATIVE BIOAVAILABILITY OF 2 CAPSULE FORMULATIONS OF MEFENAMIC-ACID

Pharmacokinetic behavior of single dose of 2 mefenamic acid capsule fo rmulations was studied in a randomized crossover design in 22 healthy male volunteers. Following ingestion of 250 mg of either of the produc ts, blood samples were obtained over a 14-hour period and the serum dr ug concentrations were determined by an HPLC assay with ultraviolet de tection at 280 nm. The parametric 90% confidence intervals of the mean value of the ratio (fendol (test)/ponstan (reference)). of pharmacoki netic parameters were 0.88 - 1.07, 0.94 - 1.19, and 0.89 - 1.16 for AU C(0-infinity) C-max and T-1/2. In each case values were within the acc eptable bioequivalence range of 0.8 - 1.25. Distribution-free point es timate for the difference in expected medians of T-max of the 2 formul ations (fendol - ponstan) was -0.5 hours with a 90% confidence interva l of -1.0 to -0.25 which overlaps with the stipulated bioequivalence r ange of +/- 0.48. The kinetic parameters are comparable to what is rep orted for mefenamic acid and there were no statistically significant d ifferences in any of them when comparing the 2 products by ANOVA on lo g-transformed data. Although the 2 products are not equivalent regardi ng the secondary parameter T-max, still the data indicate that they co uld be considered bioequivalent regarding rate of absorption (C-max), extent of absorption (C-max and AUC), and elimination (t(1/2)).