Analysis of Nicotinic Acid and Its Metabolites by HPLC-MS/MS

Abstract

Nicotinic acid is a hypolipidemic agent with pleiotropic effects.  Its drug form with controlled release leads to pyridine metabolites associated with the risk of hepatotoxicity. The aim of the present study was to introduce a HPLC-MS method for the determination of nicotinic acid, nicotinamide, nicotinuric acid, N-methylnicotin­amide, nicotinamide 1-oxide, 1-methyl-2-oxo-1,2-dihydro­pyridine-5-carboxamide, and 1-methyl-4-oxo-1,4-dihydro­pyridine-5-carboxamide in blood plasma or urine. The method is useful for the monitoring in hypolipidemic the­rapy. We have compared calibration  curves of individual metabolites using Hypercarb (graphite carbon) and Hypersil Silica (silicagel) columns. Both columns gave linear calibration curves for all the mentioned analytes (except for 1-methylnicotinamide) in the concentration range 10–2000 ng ml^–1. The calibration curve in blood plasma and urine measured with the Hypersil Silica column was linear in the range 20–4000 ng ml^–1 for all the tested analytes. The analysis time was 15 min with the column Hypercarb and 27 min with Hypersil Silica. Biological samples were extracted with sulfonated copolymer N-vinylpyrrolidone – divinylbenzene. Reproducibility of the results for biological samples varied between 0.06 % and 19.97 %.