Assessment of beta-blocking activity of low-dose bupranolol.

In the present study an investigation was made on the pharmacodynamic effect of the beta-blocking agent bupranolol in the low-dose range. Bupranolol is usually given in doses of 100 mg twice daily in the treatment of hypertension, however the dose range between 20 and 100 mg was studied using graded isoproterenol injections in healthy volunteers. A significant beta-1-blocking activity was observed for the 20 mg dose already. This effect was reduced after a treatment of 10 days. The effect increased with the higher doses, there might be a linear correlation between the logarithm of the dose and the reduction of the tachycardia after the isoproterenol injections in the low-dose range. It was concluded that using the safe and sensitive isoproterenol injection method, the clinical effect of very low doses of bupranolol may be demonstrated. The low dose might be useful to reduce the reflex tachycardia seen in the treatment of hypertension with vasodilating drugs.