LC-MS–MS Simultaneous Determination of Niacin, Niacinamide and Nicotinuric Acid in Human Plasma LC-MS–MS and Its Application to a Human Pharmacokinetic Study

A highly selective and sensitive liquid chromatographic tandem mass spectrometric (LC-MS–MS) method was developed and validated for the quantitation and pharmacokinetic study of niacin (NA) and its two metabolites niacinamide (NAM) and nicotinuric acid (NUR) in human plasma. Protein precipitation with 14% perchloric acid solution was selected for sample preparation, and ganciclovir was used as an internal standard. Separation was on a Phenomenex Curosil-PFP (250 mm × 4.6 mm, 5 μm) column by a multiple steep steps linear gradient elution with mobile phase consisting of water and methanol, both containing 0.1% formic acid, pumped at a flow rate of 1 mL min−1. The determination was optimized and carried out with positive electrospray ionization by selective multiple reaction monitoring. The method was linear in the concentration range of 15–2,000 ng mL−1 for NA, 70–2,000 ng mL−1 for NAM and 10–2,000 ng mL−1 for NUR, by standard addition calibration. The application of LC-MS–MS was demonstrated for the specific and quantitative analysis of NA, NAM and NUR in human plasma from a pharmacokinetic study in 12 healthy Chinese volunteers treated with three incremental doses of niacin extended-release/lovastatin tablets and an additional steady-state regime.