Cytochrome P450 genotypes are not associated with refractoriness to antipsychotic treatment.

Evidence validating the influence of the cytochrome P450 (CYP) 2D6 and 2C19 enzymes genetic polymorphisms in the response to antipsychotics is scarce. We examined the hypothesis that a higher prevalence of CYP2D6 and/or CYP2C19 ultra rapid metabolizers might be found among refractory schizophrenia patients. Three groups were studied: refractory and non-refractory schizophrenia patients, and healthy controls. Participants were genotyped for CYP2D6 and CYP2C19 polymorphisms and classified in metabolic phenotypes. No between-group differences in the distribution of the phenotypes were found. Therefore, our findings do not support the CYPs 2D6 and 2C19 genotyping in the prediction of therapeutic response in schizophrenia.