Reversed-phase liquid chromatographic determination of isoniazide in human urine as a test of the genetically predetermined type of biotransformation by acetylation

Abstract

A new method of determination of genetically predetermined type of biotransformation by acetylation rate using reversed-phase liquid chromatography (RP-HPLC) was described. The method is based on determination of isonicotinic hydrazide (INH) which is excreted with the patient's urine during 24 h period after oral administration of 0.4 g of the drug. INH is used as pharmacogenetic marker. Precolumn derivatization of 4-chloro-5,7- dinitrobenzofurazan is used at RP-HPLC determination of INH and a new drug phosphabenzide (diphenylphosphinylacetic hydrazide, DPPAH) with spectrophotometric detection in urine. The limit of INH detection was 0.27 μg ml-1 and the one of DPPAH was 0.82 μg ml-1. As a result of pharmacokinetic investigation it was discovered that bimodal distribution by acetylation rate for DPPAH is less apparent than in the case of INH. It is shown, that immunomodulator xymedone (N-(β-oxyethyl)-4,6- dimethyldihydropirimidon-2) is the acetylation inductor of xenobiotics.