Effect of Extended-Release Niacin on High-Density Lipoprotein (HDL) Functionality, Lipoprotein Metabolism, and Mediators of Vascular Inflammation in Statin-Treated Patients

Abstract

Background: The aim of this study was to explore the influence of extended-release niacin/laropiprant (ERN/LRP) versus placebo on high-density lipoprotein (HDL) antioxidant function, cholesterol efflux, apolipoprotein B100 (apoB)-containing lipoproteins, and mediators of vascular inflammation associated with 15% increase in high-density lipoprotein cholesterol (HDL-C). Study patients had persistent dyslipidemia despite receiving high-dose statin treatment.

Methods and results: In a randomized double-blind, placebo-controlled, crossover trial, we compared the effect of ERN/LRP with placebo in 27 statin-treated dyslipidemic patients who had not achieved National Cholesterol Education Program-ATP III targets for low-density lipoprotein cholesterol (LDL-C). We measured fasting lipid profile, apolipoproteins, cholesteryl ester transfer protein (CETP) activity, paraoxonase 1 (PON1) activity, small dense LDL apoB (sdLDL-apoB), oxidized LDL (oxLDL), glycated apoB (glyc-apoB), lipoprotein phospholipase A2 (Lp-PLA2), lysophosphatidyl choline (lyso-PC), macrophage chemoattractant protein (MCP1), serum amyloid A (SAA) and myeloperoxidase (MPO). We also examined the capacity of HDL to protect LDL from in vitro oxidation and the percentage cholesterol efflux mediated by apoB depleted serum. ERN/LRP was associated with an 18% increase in HDL-C levels compared to placebo (1.55 versus 1.31 mmol/L, P<0.0001). There were significant reductions in total cholesterol, triglycerides, LDL cholesterol, total serum apoB, lipoprotein (a), CETP activity, oxLDL, Lp-PLA2, lyso-PC, MCP1, and SAA, but no significant changes in glyc-apoB or sdLDL-apoB concentration. There was a modest increase in cholesterol efflux function of HDL (19.5%, P=0.045), but no change in the antioxidant capacity of HDL in vitro or PON1 activity.

Conclusions: ERN/LRP reduces LDL-associated mediators of vascular inflammation, but has varied effects on HDL functionality and LDL quality, which may counter its HDL-C-raising effect.

Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01054508.

Keywords: HDL functionality; LDL quality; cholesterol efflux; extended‐release niacin; inflammation; laropiprant; oxidation.

Figure 1

Study overview. Patients randomized to placebo during the first period received extended-release niacin/laropiprant (ERN/LRP) in the second period and vice versa. In each period, the ERN/LRP dose was increased from 1 g/20 mg to 2 g/40 mg after 4 weeks. SC indicates screening visit.

Figure 2

LPO generated over 3 hours on incubating LDL or LDL+HDL with CuSO₄ on treatment with ERN/LRP and placebo. HDL on both placebo and ERN/LRP markedly decreased generation of lipid peroxides, *P<0.0001. However, this antioxidant property of HDL was not enhanced by ERN/LRP therapy. Values are in median (interquartile range). ERN/LRP indicates extended release niacin/laropiprant; HDL, high-density lipoprotein; LDL, low-density lipoprotein; LPO, lipid peroxides.

Figure 3

Effect of extended-release niacin/laropiprant (ERN/LRP) (treatment) and placebo on % cholesterol efflux from J774A.1 cells over 4 hours (when control is subtracted), *P=0.045. Control is percent efflux to serum-free media.