Hydroquinidine effects on apathy and hypersomnia of patients with myotonic dystrophy

To gain new insights into the pathophysiology of myotonic dystrophy (MD), we determined whether the antiarrhythmic drug hydroquinidine could ameliorate apathy and hypersomnia in MD patients. Ten ambulatory patients were enrolled in a placebo-controlled, double-blind, crossover trial. Placebo or hydroquinidine (450 mg/day) were given orally for 6 weeks with a washout period of 6 weeks between treatments. Apathy was evaluated by the Apathy Evaluation Scale (AES) and hypersomnia by a sleep diary. Two patients withdrew in the first week of active treatment because of nausea and epigastralgia. Hydroquinidine significantly reduced AES scores and daily sleep time as compared to placebo. Thus, the antiarrhythmic drug can ameliorate apathy and hypersomnia in MD patients, but the possibility of proarrhythmia and the high frequency of cardiac disturbances in MD strongly limit the therapeutic perspective.