A NEW RADIOIMMUNOASSAY FOR HALOPERIDOL - DIRECT MEASUREMENT OF SERUM AND STRIATAL CONCENTRATIONS

Abstract

A sensitive and specific radioimmunoassay for haloperidol was developed. Antibodies were elicited in rabbits immunized with haloperidol hemisuccinate coupled to bovine serum albumin. Optimum sensitivity was obtained with a 1:4000 dilution of the antisera, permitting the detection of as little as 2.6 ng/ml of haloperidol. Major metabolities of haloperidol did not cross-react in the assay. The method does not require an extraction procedure and can be performed using as little as a 5-.mu.l sample. Haloperidol levels in rat serum and striatum were determined with this method, after the i.v. administration of different dosages of the drug. The distribution and elimination of haloperidol was linear over the dose range studied: 0.25, 0.5 and 1.0 mg/kg. Haloperidol had an elimination half-life of approximately 2.6 h at all 3 dosage levels.