Exploring the usefulness of plasma level determination and pharmacogenetics for patients treated with clozapine.

Aims: The aims of the present study were to assess the variance of plasma clozapine (CLZ) levels and to identify the influence of sociodemographic and pharmacogenetic factors on it and to introduce these tools in a clinical setting. Patients & methods: CLZ concentration was measured and genetic variants of CLZ pharmacokinetic and pharmacodynamic factors were assessed in 23 patients with psychotic disorders. Results: A significant association between mean concentration/dose ratio (C/D) and smoking status, age and weight were found. There was a significant difference in mean plasma CLZ levels and gender. The rs762551 AA genotype in smokers had a significantly lower C/D. Conclusion: In addition to classical factors, monitoring of plasma concentrations together with pharmacogenetics led to greater individualization of treatment.