COMPARATIVE PHARMACOKINETICS OF 2 BRANDS OF ATENOLOL FOLLOWING A SINGLE ORAL-ADMINISTRATION

The pharmacokinetic parameters (C-max, T-max, t(1/2), AUC(0-30h), AUC( 0-infinity)) of atenolol following a single oral administration of 100 mg of a test product (Tenolol, The United Pharmaceutical Manufacturin g Company, Amman, Jordan) were compared to those of a reference produc t (Tenormin, ICI Pharmaceuticals). The 2 products were administered ac cording to a randomized 2-way crossover design to 24 healthy male volu nteers. After drug administration, serial blood samples were collected over a period of 30 hours. Atenolol plasma concentrations were measur ed using an HPLC technique with fluorometric detection at an excitatio n and an emission wavelengths of 222 nm and 300 nm, respectively, The parametric 90% confidence intervals of the mean value of the ratio (Te nolol/Tenormin) of pharmacokinetic parameters were 0.90 - 1.12, 0.92 - 1.12, 0.88 - 1.14, and 0.91 - 1.09 for AUC(0-30h), AUC(0-infinity), C -max, and t(1/2). In each case values were within the acceptable bioeq uivalence range of 0.8 - 1.25. Point estimates of these parameters wer e 1.01, 1.02, 1.01, and 1.0. The parametric point estimate of the mean difference of T-max between the 2 formulations (Tenolol Tenormin) was 0.19 hours with a 90% confidence interval of -0.47 - 0.84, which over laps with the stipulated bioequivalence range of +/- 0.64, Thus, the 2 products could be considered bioequivalent regarding rate of absorpti on (C-max and T-max), extent of absorption (C-max and AUC), and elimin ation (t(1/2)).