Analysis of flecainide and two metabolites in biological specimens by HPLC: application to a fatal intoxication

A few days after her admittance to a hospital for a suicide attempt with benzodiazepines, a 15-year-old girl was found dead in bed. At autopsy, no specific anatomo-pathologic cause of death was identified. Systematic toxicological analysis (HPLC-DAD, GC-NPD, and GC-MS) of postmortem blood and urine revealed the presence of high concentrations of flecainide and its two major metabolites. Flecainide is a class IC anti-arrhythmic drug causing a decreased intracardiac conduction velocity in all parts of the heart. To identify and quantitate flecainide together with its metabolites in blood, urine, and other toxicologically relevant matrices, a new method was developed using high-performance liquid chromatography with diode-array detection. All compounds were separated on a Hypersil BDS phenyl column using water, methanol, and 1.5M ammonium acetate in a gradient system. Chromatographic analysis was preceded by an optimized solid-phase extraction procedure on RP-C18 extraction columns. The flecainide concentrations in blood and urine were 18.73 and 28.3 mg/L, respectively, and the metabolites were detected only in urine at the following concentrations: 9.4 mg/L for meta-O-dealkylated flecainide and 8.59 mg/L for meta-O-dealkylated flecainide lactam. Based on these results, it was concluded that the suicide was consistent with an overdose of this anti-arrhythmic drug.