Steady-state concentrations of mirtazapine, N-desmethylmirtazapine, 8-hydroxymirtazapine and their enantiomers in relation to cytochrome P450 2D6 genotype, age and smoking behaviour.

Background And Objective: Mirtazapine is a tetracyclic antidepressant drug available as a racemic mixture of S(+)- and R(-)-mirtazapine. These enantiomers have different pharmacological properties, and both contribute to the clinical and adverse effects of the drug. Cytochrome P450 (CYP) 2D6 has been implicated in the metabolism of S(+)-mirtazapine.

Gene expression of cytochrome P450 1B1 and 2D6 in leukocytes in human pregnancy.

We investigated the influence of human pregnancy on gene expression of two cytochrome P450 enzymes in white blood cells. Cytochrome P450 1B1 (CYP1B1) catalyses oestradiol 4-hydroxylation, and may participate in the endocrine regulation of oestrogens. Cytochrome P450 2D6 (CYP2D6) metabolises many commonly used drugs, and previous studies have suggested that it is induced during pregnancy.