title: Simultaneous liquid chromatographic analysis of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and nordoxepin.
abstract: A simultaneous method for the therapeutic monitoring of amitriptyline, doxepin, imipramine, and their active demethylated metabolites nortriptyline, nordoxepin, and desipramine, respectively, in plasma or serum by reversed-phase liquid chromatography (RPLC) is presented. The drugs and the internal standard (loxapine) are first extracted from 2 ml of serum into butylchloride at pH 14, and then back extracted into 200 microliter of 0.025 mol/l hydrochloric acid. An aliquot of the aqueous acid phase is injected into the chromatograph and eluted with acetonitrile-phosphate buffer (21: 79, by vol.) containing 0.6 nl of n-nonylamine per liter of phosphate buffer. The drugs are eluted in a total chromatographic time of approximately 13 min at ambient temperature and detected at 200 nm. A sensitivity of 5 microgram/l of serum for each drug is obtained. Recoveries for these drugs ranged from 77% to 103%; and the coefficient of variation (day-to-day) ranged from 4.2 to 7.8. Of 35 basic or neutral drugs tested for possible interference, only propoxyphene interferes with the analysis of nortriptyline.
mesh_terms: D000639:Amitriptyline / Q000097:blood; D000929:Antidepressive Agents, Tricyclic / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods; D003891:Desipramine / Q000097:blood; D004316:Doxepin / Q000031:analogs & derivatives / Q000097:blood; D006801:Humans; D007099:Imipramine / Q000097:blood; D009661:Nortriptyline / Q000097:blood
chemical_list: D000929:Antidepressive Agents, Tricyclic; D004316:Doxepin; D000639:Amitriptyline; D009661:Nortriptyline; C028701:desmethyldoxepin; D007099:Imipramine; D003891:Desipramine