Simultaneous gas chromatographic determination of lorcainide hydrochloride and three of its principal metabolites in biological samples.

A method is described for the determination of the antiarrhythmic drug lorcainide hydrochloride and its three main metabolites in plasma, urine, faeces and tissues from man and animals. The procedure involves the extract of the parent drug, its metabolites and the internal standard from the biological materials at different alkaline pH values, back-extraction into sulphuric acid and re-extraction into the organic phase (heptane--isoamyl alcohol). After silylation of the different phenolic and the N-dealkylated metabolites, analyses were carried out by automated gas--liquid chromatography with electron-capture detection. The method has a sensitivity limit of 5 ng for lorcainide, and 10--20 ng for the various metabolites, per millilitre of plasma. The method was applied to urine, faeces, plasma and tissue samples from man and animals. It was also suitable for automatic sample analysis.