Alprenolol in angina pectoris. A comparative study of the tablet form and slow-release formulation.

In a double-blind crossover trial in angina pectoris patients, alprenolol in a slow-release formulation (Aptin Durules) was compared with ordinary Aptin tablets. Four hundred mg per day in tablets given four times a day produced the same increase in exercise tolerance five hours after last intake as did an equivalent dose of slow-release formulation given twice per day nine hours after intake. Aptin Durules in double the dosage had a considerably greater effect. An optimal, sustained and antianginal effect of alprenolol is best achieved by giving 400 to 800 mg per day of slow-release formulation with 10 to 12 hours' dosage interval.