LLerena Adrián, Berecz Roland, Dorado Pedro, de la Garza César Sanz, Norberto Maria Jesús, Cáceres Macarena, Gutiérrez José Ramón
Department of Pharmacology, Faculty of Medicine, University of Extremadura, Avda. de Elvas s/n, 06071, Badajoz, Spain.
J Chromatogr B Analyt Technol Biomed Life Sci. 2003 Jan 5;783(1):213-9. doi: 10.1016/s1570-0232(02)00661-x.
A high-pressure liquid chromatography with ultra-violet detection method for the simultaneous determination of risperidone and 9-hydroxyrisperidone in plasma after liquid-liquid extraction has been developed. The limit of quantitation was 5 nmol/L, and the inter-day coefficient of variation was less than 8% for both compounds. The mean recoveries of risperidone and 9-hydroxyrisperidone added to plasma were 96.8 and 99.4%, with an intra-day coefficient of variation of under 5 and 6%, respectively. Studies of analytical interference showed that the most commonly co-administered antidepressants and benzodiazepines did not interfere. The method was used for the determination of the plasma concentrations of a schizophrenic patient treated daily with an oral dose of 4.5 mg risperidone. The patient suffered severe extrapyramidal side-effects after adding risperidone to his previous medication of haloperidol and levomepromazine. The risperidone plasma concentration was well above the average (182 nmol/L), which suggests that a pharmacokinetic interaction occurred, presumably due to inhibition of the enzyme CYP2D6.
