The Effect of Age on Plasma Levels of Nortriptyline

AbstractIn 109 hospitalized patients taking nortriptyline (NOR), regression of steady-state plasma levels per milligram and age revealed a positive correlation (p = 0.03). This relationship was primarily determined by patients 40 years and older, as opposed to those less than 40. There were no significant male-female differences. Eleven patients underwent a dosage change and had new steady-state levels of NOR (a low and a higher dose trial). A positive correlation was observed between NOR plasma level/dosehigh and NOR plasma level/doselow (p < 0.001), confirming linear pharmacokinetics for NOR with changing dose. These findings support lower dosing strategies for NOR in the elderly and the use of plasma monitoring for dosage adjustment.