A liquid chromatographic method for quantitating amitriptyline in brain tissue.

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 drug-free 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% (mean +/- 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 less than 0.001).