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

▼ Introduction: The eff ects 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 % confi dence 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 infl uenced 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. T hi s do cu m en t w as d ow nl oa de d fo r pe rs on al u se o nl y. U na ut ho riz ed d is tr ib ut io n is s tr ic tly p ro hi bi te d.