Pharmacological studies with slow-release formulations of oxprenolol in man

Abstract

1.) Circulatory effects of standard commercial and two slow-release preparations of oxprenolol, each containing 80 mg were compared with placebo in a double-blind randomized cross-over study in six normal subjects. 2.) After both slow-release preparations, the concentration of oxprenolol in blood was significantly less at one hour but significantly greater at 4, 8 and 12 hours than after the standard preparation. Variability of blood oxprenolol concentration between individuals was similar after all three formulations. 3.) Blood oxprenolol concentration was linearly related to the suppression of isoprenaline tachycardia and logarithmically related to the reduction in maximum exercise heart rate. 4.) The reduced maximum, but more sustained, blood oxprenolol concentration after the slow release preparations had no significant effect on the reduction of exercise tachycardia at one hour but significantly extended the duration of its activity compared with the commercial preparation. 5.) These results indicate that the pharmacological activity of beta-adrenoceptor antagonists with a relatively short duration of action may be usefully extended by slow-release formulation.