Effects of extended-release niacin on lipoprotein subclass distribution

The efficacy of extended-release niacin (niacin ER) on lipoprotein subclasses was evaluated in patients with primary hypercholesterolemia using a proton nuclear magnetic resonance method. Paired plasma samples collected at baseline and after 12 weeks' treatment with niacin ER 1,000 (n = 21) or 2,000 (n = 20) mg/day or placebo (n = 19) were available for 60 eligible patients from a previous multicenter, randomized, controlled trial. Niacin ER increased high-density lipoprotein (HDL) cholesterol and decreased low-density lipoprotein (LDL) cholesterol and very low-density lipoprotein triglycerides in a dose-dependent manner relative to placebo. Niacin ER increased large HDL particles (H5 and H4, corresponding to the HDL(2ab) fraction) without having a net effect on small HDL particles (H3, H2, and H1, corresponding to the HDL(3abc) fraction). It also decreased smaller, denser LDL particles (L1 and L2) and increased the larger, more buoyant L3 subclass. The inhibitory effect of niacin ER on very low-density lipoprotein was evident on the larger particles (V6, V5, V4, and V3 subclasses) rather than the smaller ones (V2 and V1). The results show that niacin ER produces a beneficial effect on lipoprotein subclasses, specifically decreasing the more atherogenic small, dense LDL particles and enhancing the cardioprotective large HDL particles.