Monitoring of tricyclic antidepressants in human serum and plasma by HPLC:characterization of a simple, laboratory developed method via external quality assessment

A reversed-phase high performance liquid chromatography (HPLC) method for t he determination of plasma and serum levels of amitriptyline (AMI), nortrip tyline (NORT), imipramine (IMI), desipramine (DESI), clomipramine (CLOMI), and norclomipramine (NCLOMI) is described. The assay is based upon single s tep liquid/liquid extraction of these compounds using hexane at pH 11 (reco very between 92 and 105%), a Nova-Pack C-18 HPLC cartridge column, a mobile phase composed of a phosphate buffer with 50% (v/v) acetonitrile and about 0.2% (v/v) diethylamine (final pH: 8) and solute detection at 242 nm. Usin g 1 mi of plasma or serum and econazole as internal standard, drug levels b etween 20 and 400 ng ml(-1) (about 60-1450 nM) were found to provide linear calibration graphs. For drug concentrations in the range of 70-120 ng ml(- 1) (about 240-430 nM), intraday and interday imprecisions (n = 5) were dete rmined to be < 6.0, and < 15%, respectively. Data reported include those ga thered over a 3-year period during which this assay was employed for therap eutic drug monitoring and clinical toxicology. The performance of the labor atory developed assay was assessed. via analysis of monthly samples provide d by an external quality control scheme. (C) 1998 Elsevier Science B.V. All rights reserved.