Calcium channel blockers and essential tremor.

Acute effects of two calcium blockers, nifedipine and verapamil, were investigated on the tremor activity of 8 patients with essential tremor and compared with those of propranolol and placebo. Following a single oral dose of 10 mg of nifedipine, tremor intensity of the patients was increased by 71.4 +/- 22.6%. Nifedipine also enhanced physiological tremor in 6 healthy volunteers by 56.0 +/- 21.9%. This effect of nifedipine was not correlated with the increase in heart rate or decrease in systemic blood pressure. Verapamil (80 mg) did not appreciably alter the patients' tremor activity.