Pramipexole in psychiatry: a systematic review of the literature.

To assess the risks and benefits of pramipexole in psychiatric populations. A PubMed search was performed using the keywords pramipexole and ropinirole, which identified 500 articles. All clinical studies in psychiatric populations were included in the primary review (24 articles). Studies involving other populations were then reviewed to evaluate potential risks and benefits not identified in the psychiatric studies. Effect sizes were calculated from controlled studies. Rates of intolerable side effects and manic switching were estimated by pooled analysis of controlled and uncontrolled studies. Pramipexole has a large effect size (0.6-1.1) in the treatment of both bipolar and unipolar depression with a low short-term rate of manic switching in bipolar patients (1% mania, 5% hypomania). The pooled discontinuation rate for all reasons was 9%. Pramipexole is neuroprotective and exerts beneficial effects on sleep architecture. Pramipexole is associated with 3 rare but serious side effects: sleep attacks, which have only occurred in Parkinson's disease; compulsive behaviors and pathologic gambling, which have occurred in Parkinson's disease and restless legs syndrome; and psychosis, which has occurred in both psychiatric and neurologic populations. Pramipexole is an important therapeutic option for treatment-resistant bipolar and unipolar depression; further studies are warranted to evaluate its safety in psychiatric patients.