Hair analysis of flecainide for assessing the individual drug-taking behavior.

Objective: The concentration of flecainide in hair was measured to determine its value as an index of individual drug-taking history.

Methods: Hair samples obtained from 15 patients treated with flecainide for more than 1 month were cut into 1-cm-long portions successively from its scalp end. The concentration of flecainide in each hair portion was measured using high-performance liquid chromatography.