Metoprolol and propranolol in essential tremor: a double-blind, controlled study.

Single oral doses of propranolol (120 mg), metoprolol (150 mg) and placebo were given in a randomised, double-blind fashion to 23 patients with essential tremor. Both beta blockers were significantly more effective than placebo in reducing the magnitude of tremor. The decrease in tremor produced by metoprolol (47, sem 9%, n = 23) was not significantly different from that observed propranolol (55, sem 5%, n = 23). Tachycardia on standing was antagonised by both drugs to a similar extent. These findings suggest that metoprolol may represent a valuable alternative to propranolol in the treatment of essential tremor. The data is consistent with the hypothesis that the tremorolytic effect of beta blockers in these patients may be unrelated to peripheral beta-2 adreno-receptor blockade, being possibly mediated by other central or peripheral modes of action of these drugs. However, it cannot be excluded that at the dose used, metoprolol had lost its relative cardio-selectivity and that the reduction in tremor was mediated by competitive antagonism at beta-2 receptor sites in skeletal muscle.