Effect of acebutolol, a new beta-receptor antagonist on heart rate and rate-pressure product in normal subjects.

A study on the effect of acebutolol, a new beta receptor antagonist, on the resting and post-exercise heart rate and rate-pressure product was carried out in 8 normal volunteers. Intravenous administration of 10 and 20 mg acebutolol was compared with 10 and 20 mg practolol administered at weekly intervals. In the oral study, increasing doses of acebutolol were administered over a period of 20 days. The heart rate and blood pressure was recorded before and at the completion of 4-minute exercise period. The exercise was carried out on a bicycle ergometer at 150 watt per minute for 4 minutes. In a dose to dose comparison, the potencies of acebutolol and practolol administered intravenously were of the same order, in decreasing the resting and post-exercise heart rate and rate pressure product. Their duration of action was also similar. In the oral study, the peak effect was achieved at a dosage of 200 mg per day (100 mg twice daily) of acebutolol. Acebutolol decreased the resting as well as post-exercise rate-pressure product (cardiac work load). This may be the mechanism for the reported beneficial effect in angina pectoris. Acebutolol was well tolerated and no serious side-effects were observed.