Amitriptyline Dosage Schedule, Sampling Time and Tricyclic Plasma Levels

Abstract

Summary: Plasma levels of amitriptyline and nortriptyline were similar in ten depressed patients after administration of amitriptyline hydrochloride in three divided doses or as a single daily dose. Maximum comparability of the plasma levels is achieved by sampling 12 to 16 hours after the single daily dose, or 3 to 7 hours after the morning dose on a thrice-daily schedule. Owing to the long biological half-life of these drugs, therapeutic plasma levels are maintained on a once a day dosage schedule, and the need for sustained release preparations appears questionable.