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

Abstract

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.

Results. Flecainide was detected in the 1-cm-long hair portion at the scalp end in the concentration range of 38.0–411.9 ng·mg^–1, which significantly correlated with the area under the plasma flecainide concentration versus time curve. The axial centimeter-by-centimeter distribution of flecainide along the hair shaft well reflected the individual history of drug use.

Conclusion. The present study suggests the usefulness of determining flecainide in hair to provide retrospective information on the individual drug-taking behavior qualitatively.