Frequency of Cyp2D6, 2C9, 2C19 polymorphisms in depressive and schizophrenic patients

Most psychotropic drugs are metabolized by polymorphic Cytochrome P450 enzymes (CYP2D6, 2C9, 2C19). Interindividual differences in drug response and adverse side effects might be due to genetic polymorphisms. Metabolic activity of the enzymes (PM=poor metabolizer, UM=ultrarapid metabolizer) were determined in depressive (n=208) and schizophrenic (n=528) inpatients compared to controls (517 healthy Caucasians) for CYP2D6, CYP2C19 and CYP2C9 alleles (genotyping via PCR-RFLP). In depressive patients an overrepresentation of CYP2D6UMs was detected (6,2% vs. 2,9%) whereas CYP2D6PMs were slightly underrepresented compared to controls (4,8% vs. 7%). In schizophrenic patients CYP2D6PMs were underrepresented (3,8% vs. 7%) compared to controls. No differences of CYP2C9 and CYP2C19 polymorphisms were detected between patients and controls.These results might indicate UMs are more prone to hospitalisation due to rather low drug plasma levels and, thus, therapeutic failure. PMs, however, are more likely to be treated sufficiently with lower doses.