[Determination of risperidone and 9-hydroxyrisperidone in plasma by high performance liquid chromatography]

A reversed-phase HPLC method for the determination of risperidone and 9-hydroxyrisperidone in plasma was established. Risperidone and 9-hydroxyrisperidone can be separated on a Zorbax ODS C18 column with a mobile phase of MeOH-water-ammonium acetate (mol/L)-ammonia water(3 mol/L) (300:50:3:1, volume ratios) and detected at 280 nm. The flow rate was 0.8 mL/min. The linear range was 2-600 micrograms/L, r = 0.996 for risperidone, and 2-800 micrograms/L, r = 0.998 for 9-hydroxyrisperidone. The average recovery was (98.2 +/- 3.5)% for risperidone, and (97.8 +/- 3.8)% for 9-hydorxyrisperidone. The intra-day and inter-day coefficients of variation were 4.12% and 4.83% for risperidone respectively, 4.28% and 4.81% for 9-hydroxyrisperidone respectively. The method has been used to determine risperidone and 9-hydroxyrisperidone mass concentration in patient plasma. The data obtained showed that the sensitivity and selectivity of this method were adequate for drug monitoring in clinical research.