Enantioselective analysis of citalopram and metabolites in adolescents

Studies of the antidepressant effect and pharmacokinetics of citalopram hav e been performed in adults, but the effects on children and adolescents hav e only been studied to a minor extent despite its increasing use in these a ge groups. The aim of this study was to investigate a group of adolescents treated for depression, with respect to the steady-state plasma concentrati ons of the enantiomers of citalopram and its demethylated metabolites desme thylcitalopram and didesmethylcitalopram. Moreover, the authors studied the genotypes for the polymorphic cytochrome P450 enzymes CYP2D6 and CYP2C19 i n relation to the different enantiomers. The SIR ratios of citalopram and d esmethylcitalopram found in this study of 19 adolescents were similar to st udies involving older patients. The concentration, of the R-(-)- and S-(+)- enantiomers of citalopram and desmethylcitalopram were also in agreement wi th values from earlier studies, the R-(-)-enantiomer (distomer) being the m ajor enantiomer. The results indicate that the use of oral contraceptives m ay have some influence on the metabolism of citalopram. This might be becau se of an interaction of the contraceptive hormones with the CYP2C19 enzyme.