The Impact of Tredaptive (ER Niacin/Laropiprant) Compared to Placebo on Brachial Artery Endothelial Function in Patients With Stable Coronary Artery Disease on Statin Therapy

Endothelial dysfunction reflects a vascular phenotype prone to atherogenesis and may therefore serve as a marker of an inherent atherosclerotic risk. In line with this hypothesis, dysfunction of either the coronary or peripheral vascular endothelium was shown to constitute an independent predictor of cardiovascular events, providing valuable prognostic information additional to that derived from conventional risk factor assessment. Interventions, such as risk factor modification and treatment with various drugs, including statins and niacin, may improve endothelial function leading potentially to improve prognosis.

Research over the past years has identified numerous beneficial effects of high-density lipoprotein (HDL) beyond this property. These include, but not limited to, improvement of endothelial function, anti-inflammatory, anti-thrombotic, antioxidative effects and the stimulation of endothelial regeneration. Consequently, therapeutic elevation of HDL is among the primary goals of treatment of patients with coronary artery disease (CAD). Laropiprant (LRP; Merck & Co., Inc, Whitehouse Station, NJ, USA) is a potent, once-daily, highly selective PGD2-receptor (DP1) antagonist. A combination tablet containing 1 g of extended-release niacin and 20 mg of laropiprant (ERN/LRPT) offers improved tolerability, supporting a simplified 1-2 g dosing paradigm and improved adherence. Statins and niacin improve endothelial function in CAD patients, however, there is no data yet regarding the additive effects of raising HDL-C by ERN/LRPT and statins on endothelial function in CAD patients. Thus the aim of the present study is to evaluate the impact of 3 months' administration of ERN/LRPT compared to placebo added to statins on endothelial function, assessed by brachial artery vasoreactivity, and platelet function in stable CAD patients .