Prediction and evaluation criteria in perazine therapy of acute schizophrenics. Pharmacokinetic data

Twenty-eight patients with acute schizophrenic illness received an oral daily dose of 200-800 mg perazine (Taxilan) for 4 weeks. Weekly plasma level determinations showed a constant perazine concentration from day 7 to day 28, whereas the equilibrium level of its metabolite desmethyl perazine was only achieved at day 14; on an average it amounted to twice the level of perazine. Additional measurements were carried out 2 and 4 h after administration of the morning dose on day 14. The maximal increase of the perazine concentration was usually reached after 2 h; though it varied between 7 and 240% of the morning level, a close correlation existed between minimal and maximal levels. The perazine fraction not bound to plasma proteins was found to be 3.1-5.5% on day 21. The percent improvement in target syndromes during 4 weeks of neuroleptic therapy, as documented with the AMDP system, was most marked in those patients who had perazine levels in the 100-230 ng/ml range at day 28; patients with lower or higher levels improved significantly less. Curvilinear relationships also appeared to exist between improvement and free perazine concentration as well as maximal level on day 14. With regard to total scores on the Brief Psychiatric Rating Scale or scores of higher-order factors, no significant relationship between improvement and perazine level was found. The desmethyl perazine concentration did not exhibit a significant relationship to the therapeutic result. The pharmacokinetic parameters investigated seem to have a limited influence on the clinical outcome.(ABSTRACT TRUNCATED AT 250 WORDS)