Liquid chromatographic determination of indecainide, a new antiarrhythmic drug, and its major metabolite, desisopropyl indecainide, in biological samples.

A simple, sensitive, and selective method for the determination of indecainide and its metabolite, desisopropyl indecainide, in human plasma (or serum) and urine is described. The compounds are extracted from alkalinized plasma or urine samples with ethyl acetate--hexane (9:1); the solvent is evaporated under nitrogen and the residue is reconstituted in the mobile phase. The compounds are chromatographed on a Zorbax C8 column, using 0.25 M ammonium acetate--acetonitrile--methanol--tetrahydrofuran (60:20:16:4) as the eluent at 1.5 ml/min. The effluent is monitored at 270 nm or by using a fluorescence detector (lambda exc 270 nm, lambda em 315 nm).