Sildenafil induced choreoathetosis in men with Parkinson's disease

The present report describes a case of choreoathetotic movements which were most probably induced by sildenafil in a patient with Parkinson's disease (PD) treated with levodopa/carbidopa (LD/CD).

A 56-year-old retired man was admitted to hospital because of bizarre, involuntary movements and anxiety. Before admission he had taken sildenafil 100 mg. He had a previous history of PD for 5 years and during the last 3 years he was stable with long-acting LD/CD and selegiline. He is in Stage 2 according to Hoehn and Yahr Staging of PD. The patient did not have any problems with erectile function and he took sildenafil 50 minutes after the last daily dose of LD/CD. The patient was discharged from the hospital 12 hours after the admittance without any symptoms of choreoathetosis.

Choreoathetotic dyskinesia is an adverse effect which was provoked by sildenafil administration (drug abuse) in a previously stabile responder to LD therapy, but probably had a lower threshold for dyskinesia. Predisposition for this pharmacokinetic interaction could be a short time interval between LD and sildenafil applied in high dosage.