QUANTITATIVE-ANALYSIS OF AMITRIPTYLINE AND NORTRIPTYLINE IN HUMAN PLASMA AND LIVER MICROSOMAL PREPARATIONS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple, rapid, highly selective and sensitive method for the analysi s of amitriptyline and nortriptyline in plasma and human liver microso mes is described. It is suitable for the routine analysis of large num bers of samples using readily available instrumentation and low cost c onsumables. The detection limit was 2 ng/ml for both compounds and cal ibration curves were linear over a wide range of concentrations and pa ssed through the origin. The within-batch and between-batch coefficien ts of variation for amitriptyline and nortriptyline were less than 7.4 % and 12.8%, respectively. A series of compounds, including inhibitors used for probing cytochrome P450 activity in vitro, were tested for i nterference in the assay. Only ketoconazole caused interference and th e assay was modified to allow samples containing ketoconazole to be an alysed.