Effects of Escitalopram on Plasma Concentrations of Aripiprazole and its Active Metabolite, Dehydroaripiprazole, in Japanese Patients

Abstract

Introduction: The effects of escitalopram (10 mg/d) coadministration on plasma concentrations of aripiprazole and its active metabolite, dehydroaripiprazole, were studied in 13 Japanese psychiatric patients and compared with those of paroxetine (10 mg/d) coadministration.

Methods: The patients had received 6–24 mg/d of aripiprazole for at least 2 weeks. Patients were randomly allocated to one of 2 treatment sequ­ences: paroxetine-escitalopram (n=6) or escitalopram-paroxetine (n=7). Each sequence consisted of two 2-week phases. Plasma concentrations of aripiprazole and dehydroaripiprazole were measured using liquid chromatography with mass spectrometric detection.

Results: Plasma concentrations of aripiprazole and the sum of aripiprazole and dehydroaripiprazole during paroxetine coadministration were 1.7-fold (95% confidence intervals [CI], 1.3–2.1, p<0.001) and 1.5-fold (95% CI 1.2–1.9, p<0.01) higher than those values before the coadministration. These values were not influenced by escitalopram coadministration (1.3-fold, 95% CI 1.1–1.5 and 1.3-fold, 95% CI 1.0–1.5). Plasma dehydroaripiprazole concentrations remained constant during the study.

Conclusion: The present study suggests that low doses of escitalopram can be safely coadministered with aripiprazole, at least from a pharmacokinetic point of view.

Key words

aripiprazole - dehydroaripiprazole - escitalopram - paroxetine - drug interaction

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