To the Editor:

The dopamine receptor agonist ropinirole, an effective initial therapy for mild to moderate Parkinson’s disease, has also been recently indicated for the treatment of restless legs syndrome. Ropinirole has a high affinity for all dopamine D₂ subfamily receptors and shows highest affinity for the D₃ receptor subtype (1). Studies have suggested it has antidepressant qualities in Parkinson’s disease and treatment-resistant depression, and at least two cases of mania have been documented (2, 3). To our knowledge, there have been no reports of cases of psychosis related to the use of ropinirole until now.

In clinical trials, the dopamine agonist ropinirole has produced hallucinations and confusion rated as mild (4). We provide evidence here that ropinirole may induce or exacerbate severe, acute psychosis in a patient without Parkinson’s disease. This case is not conclusive in part because of the use of quetiapine. However, the rapidity and degree of improvement weigh in favor of a strong role for ropinirole, and the likelihood of such an effect with this medication stands to reason. Given the recognized relationship of dopaminergic function to psychosis, best known through the strong antipsychotic effects of dopamine antagonists, such an effect of exacerbating psychosis by a dopamine agonist seems almost predictable. We suggest that ropinirole, like all other dopaminergic agents, be used with caution in psychotic patients and those vulnerable to psychosis.