The biphasic effect of gradually increased doses of diazepam on prolactin secretion in acute schizophrenic patients

7 acute schizophrenic patients were treated with diazepam in gradually increased doses from 30-200 mg/day/p.o. The effects on serum prolactin levels (SPL) and on the clinical improvement of these patients, evaluated by the Brief Psychiatric Rating Scale (BPRS), were studied. SPL was measured by homologous double antibody radioimmunoassay. Diazepam administered in doses of 30-100 mg during the first 7-10 days lowered SPL by 23% ± 11.4 of the pretreatment baseline while doses of 100-200 mg given for the next 4 days enhanced SPL (16% ± 26.8). During the entire period no clinical improvement was observed as measured by BPRS. However, it is possible that initial high doses of diazepam maintained for a minimum trial period of 2 weeks, might result in some significant improvement.