Comparative pharmacokinetic studies on the relative biologic availability of two propranolol preparations in patients with steady state essential hypertension

: Plasma propranolol concentrations were analyzed after Obsidan (VEB Isis-Chemie, Zwickau, GDR) (= preparation A) and another propranolol-preparation (= preparation B) in 10 patients with arterial hypertension of clinical stage I-II in a cross-over design. The concentration-time-curves (AUC0----infinity) were investigated up to 24 h after the oral intake of 40 mg of both preparations of propranolol and were nearly identical. In comparison with preparation B the relative bioavailability F was 104% for preparation A. The steady-state plasma concentrations of propranolol were within the therapeutic range of 50-100 ng/ml. They showed only interindividual variations about the factor 2-3. Peak plasma concentrations were observed 1,5-2 h after the oral application. There were no statistical differences in the pharmacokinetic parameters between the both preparations. The rate of elimination constants of 0,065 to 0,073 h-1 after preparation A and B explain the long duration of the therapeutic efficacy during chronic treatment.