Impact of polymorphisms of cytochrome-P450 isoenzymes 2C9, 2C19 and 2D6 on plasma concentrations and clinical effects of antidepressants in a naturalistic clinical setting

• Published in: European journal of clinical pharmacology 2004-07, Vol.60 (5), p.329-336
• Main Authors: GRASMÄDER, Katja, VERWOHLT, Petra Louise, RIETSCHEL, Marcella, DRAGICEVIC, Aleksandra, MÜLLER, Matthias, HIEMKE, Christoph, FREYMANN, Nikolaus, ZOBEL, Astrid, MAIER, Wolfgang, RAO, Marie Luise
• Format: Article
• Language: English
• Subjects: Antidepressive Agents - blood; Antidepressive Agents - therapeutic use; Biological and medical sciences; Cytochrome P-450 Enzyme System - genetics; Depressive Disorder - blood; Depressive Disorder - classification; Depressive Disorder - drug therapy; Female; Genotype; Humans; Isoenzymes - genetics; Linear Models; Male; Medical sciences; Middle Aged; Neuropharmacology; Pharmacogenetics; Pharmacology. Drug treatments; Polymorphism, Genetic; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Severity of Illness Index
• ISSN: 0031-6970; 1432-1041
• DOI: 10.1007/s00228-004-0766-8

This evaluation focuses on polymorphisms of the cytochrome-P450 (CYP) isoenzymes 2C9, 2C19 and 2D6 and their association with plasma concentrations within a typical clinical setting. Side effects and treatment response were analysed in an exploratory approach in poor and ultra-rapid metabolisers. We analysed 136 Caucasian depressed inpatients treated with amitriptyline, citalopram, clomipramine, doxepin, fluvoxamine, mirtazapine, paroxetine, sertraline and venlafaxine, who underwent weekly plasma concentration measurements, assessment of the severity of illness and side effects during their stay in the hospital. Patients were genotyped with respect to CYP2C9 alleles *1 and *2, the CYP2C19 alleles *1, *2 and *3 and the CYP2D6 alleles *1 to *9 and CYP2D6 gene duplication. CYP2D6 poor metaboliser genotype and co-medication with inhibitors of CYP2D6 were associated with higher plasma concentrations than the drug-specific median plasma concentration when normalised to dose; plasma concentrations of CYP2C19 extensive metabolisers and smokers were significantly lower than the drug-specific median. Five of the six CYP2D6 poor metabolisers experienced side effects. Response was not associated with plasma concentrations above or below the lower limit of a presumed therapeutic range. These data indicate a significant influence of the CYP2D6 genotype, minor influence of the CYP2C19 genotype and no influence of the CYP2C9 genotype on plasma concentrations of patients taking mainly second-generation antidepressants. Because of the good tolerability of the latter and the flat dose-response relationship, genotyping should only be considered in cases of suspected side effects.