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We report a method for simultaneous measurement of five commonly used tricyclic antidepressant drugs (doxepin, desipramine, nortriptyline, imipramine, and amitriptyline) in serum by paired-ion high-performance liquid chromatography, with use of a reversed-phase column and ultraviolet detection at 254 nm. The drugs are extracted from 2 ml of serum at pH 14 into hexane/isoamyl alcohol (99/1 by vol) and re-extracted into 200 microliter of 0.1 mol/liter HCI. An aliquot of the aqueous acid phase is chromatographed with use of a methanol/acetonitrile/water (41/15/44) solvent system, containing 5 mmol of pentanesulfonic acid per liter of phosphate buffer (0.1 mol/liter, pH 6.5), at a flow rate of 1,5 ml/min. Analytical recoveries of the drugs from serum increase with increasing concentration, from 62% at 25 microgram/liter to 93% at 300 microgram/liter. Linear response is observed for drug concentrations up to 1500 microgram/liter and the detection limit is 2-3 microgram/liter. Within-run precision ranges from 1.4 to 2.9% and day-to-day precision from 1.7 to 7%, depending on the specific drug. The entire procedure can be completed within 45 min and is well adapted to the routine clinical laboratory. Of 48 common basic and several neutral drugs tested for possible interferences, only three benzodiazepines, three phenothiazines, and three antihistamines interfere with the assay of doxepin, desipramine, and nortriptyline, respectively.

We describe here a rapid and comprehensive screening method for 40 commonly used sedatives and tranquilizers with use of gas-liquid chromatography. Barbiturates, nonbarbiturate sedatives, and tranquilizers of the phenothiazine, benzodiazepine, and dibenzazepine type can be both identified and measured in serum. A simple solvent extraction at different pH values, with subsequent solvent partition, effects a preliminary separation into acid, neutral, and basic drugs. The three fractions are separated on two standard 180-cm glass columns: acid and neutral drugs with the liquid phase XE-60 (3.5%) and basic drugs with the liquid phase OV-17(3%). Sera from more than 50 patients have been analyzed by this technique, and the concentrations of several sedatives and tranquilizers are reported.

1 Efficacy and tolerability of brotizolam (0.25 and 0.5 mg) were compared over a 6-day period with nitrazepam (5.0 mg) in middle-aged patients (less than 65 years) with sleep disturbances requiring medication. The study was double-blind and randomised with a cross-over design. 2 Each preparation reduced sleep onset latency and frequency of awakenings, and improved quality and duration of sleep as well as subjective condition on awakening. Brotizolam 0.25 mg was found to be equally effective as 0.5 mg, and so the lower dose is recommended for the middle aged.

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