Clonidine versus propranolol in the treatment of essential tremor. A double-blind trial with a one-year follow-up

Introduction: To compare the efficacy of clonidine vs propranolol in the control of essential tremor, a double-blind randomized controlled trial with a one year follow-up was designed to obtain 80% power and 95% confidence level. Patients and methods: The participants (186 patients with the essential tremor diagnosis) were recruited from the community, 122 (65.6%) of these patients completed the trial. They were assessed using a Clinical-Evaluation Scale for Tremor and were examined 5 times, once at baseline and 4 times during the treatment phase. We used ANOVA with Bonferroni corrections, a p value of < 0.01 was considered significant. Dropouts due to side effects were compared using the Fisher's exact X (2) test for two tails, a p value of < 0.05 was considered statistically significant. Results: Propranolol as well as clonidine (p = 0.005) proved to be statistically efficacious (p = 0.0005). Propranolol was not more efficacious than clonidine (p = 0.4). Dropouts were significantly higher in the clonidine group, 22 patients (p = 0.006) and the most common undesirable side effect in this group was mouth dryness (in 8 patients). Conclusions: Clonidine was useful; when both drugs were compared propranolol was not shown to be superior to clonidine. Based on the results of this study, clonidine appears to be a good option for the treatment of mild to moderate essential tremor.