RESUMO
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 x 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.