A simple high-performance liquid chromatographic method for the routine measurement of flecainide in plasma.

A simple and sensitive high-performance liquid chromatographic method for the analysis of flecainide in plasma has been developed. Alkalinized plasma was extracted with 1-chlorobutane and then back extracted into dilute phosphoric acid. An aliquot of the aqueous acid layer was injected onto the HPLC column and the eluent monitored at 297 nm. A phenyl reversed-phase column was used for the separation. The mobile phase was 42% acetonitrile and 58% 20mM sodium acetate solution, with the pH of the mobile phase adjusted to 6.5. The recovery of flecainide was 88.5%, and the coefficient of variation of two quality control (0.2 mg/L and 1.0 mg/L) samples analyzed on a within-day basis (N = 10) was 3.0% in both cases. The coefficient of variation for the two quality control samples analyzed on a between-day basis (N = 10) was less than 10% in both cases. The limit of sensitivity for the assay was 0.033 mg/L. A variety of other drugs likely to be used in patients with cardiovascular disease were screened and found not to interfere with the assay.