Acute and subchronic effects of low-dose bromocriptine in haloperidol-treated schizophrenics

The effects of the acute (within 24 hr) and subchronic (21 days) addition of low-dose bromocriptine (2.5 mg/day) were compared to placebo in schizophrenic patients treated concomitantly with haloperidol. After 24 hr patients on bromocriptine (n = 15) showed a mean improvement of 29% in the total score of the Brief Psychiatric Rating Scale (BPRS) as compared to 14% in the placebo group (n = 15) (p less than 0.10). The acute improvement correlated negatively with bromocriptine plasma levels; patients with the highest reduction in BPRS score had the lowest plasma levels (between 50 and 150 pg/ml) at 60, 90, and 120 min after intake. The improvement in the bromocriptine group continued until the 10th day of the trial, when a nonsignificant increase in the total BPRS score took place. Analysis of Variance of the overall BPRS improvement during the 21 days revealed no significant difference between both patient groups. Our results give modest support to the idea of an acute antipsychotic response to low-dose dopamine agonists in neuroleptic-treated patients, but fail to support their clinical usefulness in the subchronic treatment of schizophrenia.