Reduced haloperidol/haloperidol ratio and clinical outcome in schizophrenia: preliminary evidences.

1. The possible influence of haloperidol and its metabolite plasma levels on clinical outcome in schizophrenic patients was evaluated. 2. 18 schizophrenic inpatients diagnosed according to DSM III, were treated with conventional haloperidol p.o. for four weeks. 3. Plasma levels of haloperidol and its reduced metabolite were measured by mass-spectrometry assay. Clinical outcome was evaluated by BPRS. 4. Cluster analysis only considering BPRS improvement and reduced haloperidol/haloperidol ratio was able to discriminate two groups of patients: one of non responders and the other of responders. The former group presented higher ratios than the latter. 5. Reduced haloperidol/haloperidol ratio could be considered as a good marker for prediction of the clinical outcome.