QTc Time Correlates with Amitriptyline and Venlafaxine Serum Levels in Elderly Psychiatric Inpatients.

Many antidepressants cause QT prolongation but the classification of cardiac risk of these drugs varies markedly in different published lists. This retrospective study analyzed the correlation of QTc time with amitriptyline and venlafaxine serum level in elderly psychiatric inpatients. Elderly inpatients aged≥65 years for whom venlafaxine or amitriptyline serum level had been measured were selected retrospectively from a therapeutic drug monitoring database and screened for an electrocardiogram measurement at the time of blood withdrawal. The correlation of amitriptyline or venlafaxine serum levels with QTc time was examined by using Pearson's correlation analysis. Amitriptyline serum levels (n=11) correlated significantly with QTc time (r=0.918, p<0.001, CI 95%). Venlafaxine serum levels (n=27) also correlated significantly with QTc time (r=0.382, p<0.05, CI 95%). Amitriptyline and venlafaxine induce QT prolongation depending on drug concentrations in blood. Its extent, however, is very low when drug serum levels are within the therapeutic range. Future pharmacokinetic studies that correlate drug serum level and QT time should classify the cardiac risk of drugs based on the grade of the regression line in relation to the therapeutic range.

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© Georg Thieme Verlag KG Stuttgart · New York.

Déclaration de conflit d'intérêts

Christoph Hiemke has received speaker’s and consultancy fees from Janssen, Stada, and Servier. He is managing director of the psiac GmbH (www.psiac.de), which provides an Internet-based drug-drug interaction program. He reports no conflict of interest with this publication. All other authors declare no conflicts of interest as well. The research study did not receive funds or support from any source.