Plasma/RBC haloperidol ratios and improvement in acute psychotic symptoms.

In a double-blind controlled study, 20 acutely psychotic inpatients were treated with different haloperidol dosage regimens. Over a 24-hour period, 10 of the patients were treated with rapid intramuscular neuroleptization at 10 mg per dose and 10 at 2 mg per dose. The patients were then treated for 6 more days with an oral dose equivalent to that given over the first 24 hours of treatment, with doctor's choice adjustments as needed. Behavioral change was rated using the Brief Psychiatric Rating Scale (BPRS). Blood samples drawn at baseline and late in the treatment were assayed for plasma and red blood cell haloperidol levels. Although neither of these variables showed a significant correlation with behavioral improvement, the ratio of plasma/RBC haloperidol levels significantly correlated with improvement.