title: Gas-chromatographic analysis for therapeutic concentrations of amitriptyline and nortriptyline in plasma, with use of a nitrogen detector.
abstract: We describe a gas-chromatographic procedure for the simultaneous determination of amitriptyline and its active metabolite, nortriptyline, in therapeutic concentrations in human plasma, with use of a nitrogen detector. Both drugs are extracted at pH 10.5 into hexane/isoamyl alcohol, back-extracted into dilute HCl, and re-extracted into hexane/isoamyl alcohol after alkalinization of the HCl. The solvent is evaporated and the residue gas-chromatographed. Protriptyline is used as the internal standard. As little as 5 mug of amitriptyline or nortriptyline can be detected per liter of plasma. The coefficients of variation, for a concentration of 200 mug/liter, are 4.6% and 4.3% within-day and 8.6% and 3.4% day-to-day for amitriptyline and nortriptyline, respectively. The procedure was applied to patients receiving therapeutic doses of both drugs and also to patients who had taken overdoses of amitriptyline.
mesh_terms: D000639:Amitriptyline / Q000097:blood* / Q000506:poisoning; D002849:Chromatography, Gas / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005069:Evaluation Studies as Topic; D006801:Humans; D008832:Microchemistry; D009584:Nitrogen; D009661:Nortriptyline / Q000097:blood*
chemical_list: D000639:Amitriptyline; D009661:Nortriptyline; D009584:Nitrogen