Propranolol and essential tremor: rôle of the membrane effect

d-propranolol is almost devoid of beta-blocking effect but has the same membrane stabilizing properties as the dl-form. In order to study the importance of membrane stabilizing activity versus beta blockade in the therapeutical effect of propranolol on essential tremor, we compared d-propranolol with dl-propranolol in 24 patients in a placebo-controlled double-blind cross-over study. dl-propranolol reduced tremor intensity better than d-propranolol. The d-form did not significantly differ from placebo in its effects on tremor, although it did reduce the heart rate slightly. It is concluded that the membrane effect is not important in the therapeutic effect of propranolol in essential tremor.