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[CYP2D6 gene polymorphism in psychiatric patients resistant to standard pharmacotherapy]
M Zabrocka1, G Woszczek, M Borowiec
1I Kliniki Psychiatrycznej AM w Lodzi.
Abstract:
The debrisoquine polymorphism is a genetic variation in oxidative drug metabolism mediated by CYP2D6 gene, characterized by two phenotypes, the extensive metabolizer (EM) and poor metabolizer (PM). PM phenotype is inherited as autosomal recessive trait and occurs in 5-10% of Caucasian population. It is associated with the inefficient metabolism of over 30 drugs, including many psychotropic drugs. Clinical studies shown that PM are at higher risk than EM of adverse reactions to these drugs. We genotyped 22 psychiatric patients in whom standard pharmacotherapy had failed or drug adverse events occurred and in 14 patients in whom standard therapy was successful. CYP2D6 polymorphic alleles were identified using allele specific nested PCR reaction. The PM genotype was found in 4 of 22 (18%) patients resistant to standard pharmacotherapy and in none of 14 patients with improvement after standard therapy. Unsuccessful standard psychotropic drugs therapy in psychiatric patients may be associated with PM phenotype.
Insights
Poor metabolizer (PM) phenotype, linked to CYP2D6 gene variations, is associated with ineffective psychotropic drug treatment in psychiatric patients. Genetic testing for this metabolic trait may improve patient outcomes.
Area of Science:
- Pharmacogenetics
- Clinical Pharmacology
- Psychiatric Genetics
Background:
- The debrisoquine polymorphism, involving the CYP2D6 gene, defines extensive metabolizer (EM) and poor metabolizer (PM) phenotypes.
- PM phenotype, an autosomal recessive trait in 5-10% of Caucasians, impairs metabolism of over 30 drugs, including many psychotropic medications.
- Poor metabolizers (PM) face a higher risk of adverse drug reactions compared to extensive metabolizers (EM).
Purpose of the Study:
- To investigate the association between CYP2D6 genotype and treatment outcomes in psychiatric patients.
- To determine if the poor metabolizer (PM) phenotype correlates with treatment resistance or adverse events in psychiatric pharmacotherapy.
Main Methods:
- Genotyping of CYP2D6 polymorphic alleles using allele-specific nested PCR.
- Comparison of CYP2D6 genotypes in psychiatric patients with failed pharmacotherapy or adverse events versus those with successful treatment.
Main Results:
- The poor metabolizer (PM) genotype was identified in 4 out of 22 (18%) psychiatric patients with resistant standard pharmacotherapy.
- None of the 14 patients who showed improvement with standard therapy possessed the poor metabolizer (PM) genotype.
- A higher prevalence of the PM genotype was observed in patients experiencing treatment failure.
Conclusions:
- Unsuccessful psychotropic drug therapy in psychiatric patients may be linked to the poor metabolizer (PM) phenotype.
- CYP2D6 genotyping could be a valuable tool for personalizing psychiatric pharmacotherapy.
- Identifying PM individuals may help predict and prevent adverse drug reactions and treatment failures.