Time course of a single oral dose of propranolol in essential tremor.

We studied the effects of a single oral dose (120 mg) of propranolol on essential tremor in 12 patients. Postural hand tremor was recorded by an accelerometer, and its amplitude and frequency determined by spectral analysis. Variable patterns of individual responses gave a mean reduction of tremor amplitude of 50% at 2 hours. Tremor was suppressed as long as 8 hours in some patients. Similar tremor reduction was found on chronic therapy. Even without treatment, tremor amplitude varied from 30 to 50%. A single oral dose of propranolol produces a rapid and sustained reduction of essential tremor, but there are diurnal fluctuations of tremor intensity regardless of treatment.