Effects of niacin extended-release and fenofibrate on endothelial function

Aim: Niacin and fenofibrate are to date the most effective available HDL-C raising therapies. We examined the effects of niacin extended-release (ER) and fenofibrate treatment on endothelial function. Methods: In a multicenter, randomized, open-label, cross-over study, dyslipidemic subjects were included; 24 with low HDL-C (<40 mg/dL) and 42 with normal HDL-C (40-59 mg/dL) at baseline, received 6 weeks’ treatment with niacin ER (0.5 g/d then 1 g/d) and fenofibrate (160 mg/d) with 4 weeks’ wash-out between treatments. Lipoprotein composition and particle size distribution were determined using NMR. Endothelial function was assessed by ultrasound brachial flow mediated dilatation (FMD) at start and end of the 6 week treatment periods. Between treatment effects were compared using ANCOVA. In slope analyses within treatments, each of the lipids and lipoproteins were correlated with %FMD, both at baseline and at end of treatment Results: Complete FMD datasets of 19 niacin ER and 17 fenofibrate treatments were available. There was no difference in FMD between treatments (p>0.2). The slope analyses, however, showed correlations between lipids and FMD, the strongest correlations occurred in the niacin ER group. In particular HDL-C (p=0.032), HDL particle size (p=0.009) and LDL sizes correlated with FMD upon niacin ER treatment. Conclusions: There were no differential effects between niacin ER and fenofibrate on endothelial function, however slope analyses revealed lipid modification by niacin ER and (to a lesser extent) fenofibrate can favorably improve endothelial function.