Haloperidol plasma levels and clinical response in paranoid schizophrenics.

The relationship between haloperidol plasma levels, plasma prolactin, and therapeutic efficacy was evaluated in 20 paranoïd schizophrenics in a fixed-dose study for 6 weeks. We found a significant intrapatient cross-correlation of therapeutic efficacy, as measured by decrease in MSS and BPRS rating scales and time-dependent haloperidol and prolactin changes, which were tested at weekly intervals. However, no significant curvilinear relationship was present between steady-state haloperidol plasma levels and MSS and BPRS improvement scores. Our data do not furnish clear-cut evidence in favor of the existence of a therapeutic window for haloperidol plasma levels in paranoïd schizophrenia.