Bioequivalence of Fexofenadine Tablet Formulations Assessed in Healthy Iranian Volunteers

Background and objective: Many drug products containing the same amount of active drug are made and marketed by more than one pharmaceutics manufacturer. Since the quality of final drug product is affected by the source of ingredients, type and amount of excipients and manufacturing process, bioequivalence studies are used to determine the bioavailabillity and characterize the pharmacokinetics of the new formulation relative to a reference formulation. In the present study the bioavailability of a new capsule formulation of fexofenadine (CAS 153439-40-8) was compared to a reference formulation in 12 healthy male volunteers. Methods. The blood samples were collected at different time points. After centrifugation and decanting the plasma, the drug was extracted using a mixture of diethyl ether/isopropyl alcohol (5:95 %v/v). Then the samples were dried at 45 degrees C under nitrogen and finally, after dissolving the dried sample in mobile phase, the plasma drug concentrations were determined using HPLC. The pharmacokinetic parameters (C-max, AUQ(0)(t), AUC(0)(infinity)) were statistically compared by analysis of variance (ANOVA) for test and reference formulations and no statistical differences were observed. Results and Discussion: The maximum plasma concentration (C-max) of fexofenadine was 1206.3 +/- 619.0 ng/ml for the test and 1172.6 +/- 493.7 ng/ml for the reference formulation. The mean AUC(0-infinity) of fexofenadine was 8911.4 +/- 3870.0 and 9363.9 +/- 2668.0 ng . h/ml for the test and reference formulation, respectively. The calculated 90 % confidence intervals for the mean test/reference ratios of mentioned parameters were 90.0-113.9, 86.9-109.5 and 80.8-102.8, respectively, which are in the bioequivalence range. Conclusion: Based on the obtained re suits the two fexofenadine formulations are considered to be equivalent.