[Application of a method of analysis using high performance liquid chromatography of isoniazid and acetylisoniazid to determine the phenotype of acetylation].

The described method is adapted from Moulin to measure plasma levels of isoniazid (INH) and acetylisoniazid (AINH) after extraction, HPLC separation and UV detection (254 nm). INH and AINH plasma levels of 109 patients aged between four months to 87 years were measured, allowing dosage individualization. The ratio of AINH to INH (Rm) three hours after administration was calculated. Rm allows determination of the patient acetylation phenotype: in fast acetylators with INH half-life shorter than 1.8 h, Rm is greater than 0.77 and in slow acetylators with INH half-life longer than 1.8 h, Rm is less than 0.48.