Relationship between clinical efficacy and plasma concentration-dose ratio of risperidone in patients with schizophrenia.

This study aimed to retrospectively explore the relationship between clinical efficacy and plasma concentration-dose ratio of risperidone (RIS) in 252 patients with schizophrenia taking RIS orally. After the same dose of RIS treatment, the plasma concentration of RIS/9-hydroxyrisperidone (9-OH-RIS), the total plasma concentration of RIS, and the ratio of the steady-state plasma concentration to the daily dose of the total active product (C/D) showed individual difference. The RIS plasma concentration was significantly higher in patients taking high doses than those taking lower doses ( P  = 0.003). There was a statistically significant difference in C/D ratio between males and females ( P  = 0.003). There were significant differences in ratio of C/D and the total plasma concentration of RIS between patients under 60 years and over 60 years ( P  = 0.016; P  = 0.005). Logistic regression analysis showed that the therapeutic effect and adverse reactions of RIS were correlated with the ratio of C/D in patients with schizophrenia ( P  = 0.038; P  < 0.001). It has been suggested that the importance of monitoring of the plasma concentration of RIS in patients with schizophrenia and the ratio of C/D may be used as the reference for RIS personalized treatment.