PHARMACOKINETIC STUDY OF RISPERIDONE. APPLICATION OF A HPLC METHOD WITH SOLID PHASE EXTRACTION

A new, simplified solid phase extraction procedure for the determination of risperidone and 9-hydroxyrisperidone in human plasma has been developed. This method involves the use of an optimized extraction protocol developed in Waters OASIS ® HLB 30mg 1cc extraction columns using 1 mL of human serum. Separation was performed by HPLC using a Waters XTerra RP-18 (5 µm, 150x4,6 mm) column with a mobile phase consisting in acetonitrile – potassium dihydrogen phosphate 50 mM pH 3.4 (27/73). UV detection at 278 nm was used to quantify analytes, encountering good linearity (r2> 0.999) in the 2-100 ng/mL concentration range. The mean recovery was 92.4 % and 92.8 % for risperidone and 9-hydroxyrisperidone respectively, with an intraday – interday precision below 7%, and accuracy below 115 %. The method has been successfully applied in pharmacokinetic studies that require a large sample number