Pramipexole as adjunct to haloperidol in schizophrenia. Safety and efficacy.

Pramipexole, a presynaptic dopamine D2/D3 autoreceptor agonist, has been given to haloperidol-treated patients with schizophrenia (n = 15) in an effort to ameliorate residual positive and negative symptoms that have not been satisfactorily influenced by haloperidol alone. Total scores of the positive and negative symptom scale (PANSS) decreased by more than 20% in 9 of 15 patients (reduction of total score: 22-62%). Serious adverse events did not occur. Three of the 15 patients dropped out due to worsening of schizophrenia. Insomnia, as the most frequent side effect, occurred in 4 patients. No clinically relevant electrocardiographic and laboratory changes were reported. This study supports the safety of the treatment of schizophrenia with pramipexole and haloperidol as a combination therapy. However, further clinical studies are required to support these preliminary findings.