Association between body weight and serum concentration of antidepressant drugs

Abstract

Body weight may affect pharmacokinetic parameters and have a relevant impact on the serum concentration of a drug. Despite highly varying body weight and weight changes by depression as well as by antidepressant treatment, studies are lacking which evaluate the relation between the patientʼs body weight and the serum concentration of drugs. Therapeutic Drug Monitoring (TDM) analyses from 2009 to 2010 in a naturalistic clinical setting were retrospectively analysed by Spearmanʼs Rho correlation. TDM-analyses from patients treated with amitriptyline (AMI, n = 414), citalopram (CIT, n = 129), clomipramine (CLM, n = 73), doxepine (DOX, n = 145), escitalopram (ESC, n = 110), fluoxetine (FLX, n = 135), mirtazapin (MIR, n = 448) and venlafaxine (VEN, n = 409) were considered. Dose-corrected serum concentrations (of the active moiety) did significantly correlate negative with body weight in patients treated with AMI (r = −0.135, p = 0.006), CIT (r = −0.216, p = 0.014), DOX (r = −0.315, p < 0.001), FLX (r = −0.185, p = 0.034), MIR (r = −0.098, p = 0.038) and VEN (r = −0.219, p < 0.001), but not in CLM and ESC treated patients. In contrast to a previous study with no significant correlations between body weight and serum concentrations of antidepressant drugs we found significant associations for the majority of antidepressants. This might be caused by the higher number of included patients which better differentiates the influence of body weight on serum concentration from other factors like sex, age or smoking habits.