Serum haloperidol and neuroleptic receptor levels in chronic psychosis

Serum haloperidol and serum dopamine blocking activity were measured, and steady state levels were compared in 22 chronic male schizophrenic patients. Haloperidol levels were measured by high pressure liquid chromatography (HPLC), and dopamine blocking activity was measured by a radioreceptor assay (NRRA). Clinical status was determined by the Brief Psychiatric Rating Scale (BPRS) and the Abnormal Involuntary Movement Scale (AIMS). Patients were stabilized on individual doses of haloperidol for at least three weeks and dosages ranged from five to 200 mg per day. All measures were determined on two occasions, one week apart. All measures (AIMS, BPRS, HPLC, and NRRA) showed a high degree of repeated test reliability. The behavioral measures showed a high degree of interobserver reliability on both occasions. There were significant correlations at both time points among haloperidol dosage, serum haloperidol levels, and dopamine blocking activity. Although the correlations between serum levels measured by HPLC and NRRA were positive and significant on both occasions, they never accounted for more than 58 percent (coefficient of variation) of the total variance.