Effect of ethosuximide on rest tremor in the MPTP monkey model

Based on the hypothesis that low-threshold calcium conductance in the thalamus might be involved in the pathophysiology of parkinsonian tremor, ethosuximide was given chronically to a monkey previously treated with MPTP and displaying exceptionally a typical rest tremor. After 5 days of daily treatment, the tremor was reduced by 60%. Diltiazem and verapamil which act on different calcium channels had no such effect. Ethosuximide also potentiated the anti-tremor effect of the dopamine D2 agonist LY-171555.