Direct microtitre plate radioimmunoassay of savoxepine in unextracted plasma

An original solid phase method for direct radioimmunoassay of the antipsychotic savoxepine (CGP 19 486 A) in plasma has been developed which does not require the extraction of the parent drug with organic solvents. The assay showed good reproducibility over the working concentration range 1.9-30.6 nmol/l with intra- and inter-assay coefficients of variation less than or equal to 16 %. The procedure, which requires only small volumes of plasma (10 mu l), is simple to handle and well suited for routine analysis. The method allowed to investigate the pharmacokinetics of savoxepine in schizophrenic patients given low oral doses of the drug.