Gas-chromatographic analysis for therapeutic concentration of imipramine and disipramine in plasma, with use of a nitrogen detector.

We describe a method for the simultaneous gas-chromatographic analysis of imipramine and desipramine (the active N-desmethyl metabolite) at therapeutic concentrations in human plasma, with use of a nitrogen detector. Imipramine is measured as the unchanged base and desipramine as its N-tribluoroacetyl derivative. Promazine is the internal standard. The lower limit of sensitivity is 5 mug/liter for each drug, and the within-day coefficients of variation for the determination of imipramine and desipramine, respectively, are 6.0% and 3.3%. We measured concentrations of these drugs both in patients receiving therapeutic doses of imipramine and in those who had ingested an overdose.