Prediction of steady-state plasma levels of amitriptyline and nortriptyline from a single dose 24 hr. level in depressed patients.

Amitriptyline and nortriptyline plasma levels were measured in depressed outpatients 24 hours after a single dose of amitriptyline and following chronic dosing to steady state. Plasma levels of amitriptyline and nortriptyline measured after the single dose correlated highly with steady state plasma levels. Full use as a test to rapidly place patients on a "therapeutic" dosage of drug will need to await a clear delineation of the relationship between blood levels and clinical response for amitriptyline.