Objective: The aim of the present retrospective pilot study was to examine the clinical impact of the cytochrome P450 (CYP) enzyme CYP2D6 poor metabolizer (PM) genotype in patients taking antipsychotic medication. The impaired metabolic capacity of the PM genotype results in higher steady-state plasma concentrations at a given dose, thus increasing the risk of toxic effects from medication.
Methods: We identified 18 PM patients with a schizophrenia spectrum diagnosis from a clinical database covering all patients who have been analyzed in an ongoing standardized CYP2D6 screening program.