Determination of risperidone and 9-hydroxyrisperidone in human plasma by high-performance liquid chromatography with electrochemical detection.

A method for the determination of risperidone and its active metabolite 9-hydroxyrisperidone in human plasma has been developed. The procedure involved a multi-step liquid-liquid extraction with an internal standard. The parent drug and its metabolite were separated on a cyano column used in the reversed-phase model. The coulometric detection allows quantification in the range 2-100 ng/ml. The precision, accuracy and specificity have been checked, and show that the method is reliable for clinical studies.