Discrepancies between pharmacokinetic studies of amitriptyline

In this article, studies on the disposition of amitriptyline after administration of a single dose, as well as following long term administration are reviewed. While long term studies showed bias towards a higher mean apparent oral clearance, studies in normal subjects nevertheless indicated a higher apparent oral clearance than that calculated from steady-state concentrations in depressed patients. Methodological issues could account for some of the discrepancies in mean values of the pharmacokinetic parameters of amitriptyline. Broad individual variability in the elimination rate of amitriptyline has been confirmed but could not be attributed to the clinical characteristics of the subjects.