A liquid chromatographic method for quantitating amitriptyline in brain tissue

Abstract

A previously reported method for measuring tricyclic antidepressants (TCA) in plasma was modified to measure TCA, specifically amitriptyline (AMI) and nortriptyline (NOR) in rat brain tissue. Brains obtained from drugfree and AMI-treated rats were extracted and assayed using a Waters high-performance liquid chromatograph. Drug-free brain tissue contained no substances which interfered with the assay of these TCAs. Drug recovery averaged 90±3.4% (x±SEM). Seven intra-run assays of a spiked brain tissue sample yielded coefficients of variation of 2.7% for AMI and 1.8% for NOR. Seven inter-run assays of the same sample varied 4.2% for AMI and 3.5% for NOR. Five separate assays of a brain homogenate sample spiked with 50 ng/ml of drug yielded values of 50±2.1 SEM ng/ml for AMI and 54±1.1 SEM ng/ml for NOR. Standard curves were linear when constructed from samples in a concentration range of 250–3,000 ng/g wet weight tissue (r=0.96, P<0.001).