Effects of niacin and Niaspan on HDL lipoprotein cellular SR-BI–mediated cholesterol efflux

BackgroundNiacin, the lipid-regulating agent with the longest therapeutic experience, has been demonstrated to both raise high-density lipoprotein cholesterol (HDL-C) levels and to diminish the risk of atherosclerosis and its vascular complications.ObjectiveThe present study was carried out to explore niacin’s effect on scavenger receptor class B type I (SR-BI)–mediated cholesterol efflux, a component of reverse cholesterol transport, using an in vitro model system.MethodsThirty frozen samples from a large randomized, multicenter trial comparing crystalline niacin, extended-release niacin (Niaspan), and placebo were analyzed for SR-BI efflux.ResultsBoth the extended-release and crystalline niacin demonstrated significant increases in HDL-C (approximately 50%) over baseline values compared to the placebo group (14%). This was associated with a significant increase in SR-BI efflux of 2.7% and 3.4% for extended-release niacin and niacin, respectively, compared to placebo (0.4%). Although, there was no relationship between HDL-C and SR-BI efflux at baseline or at the end of treatment, there was a linear relation between the changes in HDL-C and SR-BI efflux (r = 0.58, P < 0.002).ConclusionThis study suggests that niacin has a beneficial effect on SR-BI efflux that is related to the change in level of HDL-C.