Atherosclerosis and its associated coronary heart disease is the leading cause of death in the industrialized world. Risk for development of coronary heart disease has been shown to be strongly correlated with certain plasma lipid levels. Lipids are transported in the blood by lipoproteins. The general structure of lipoproteins is a core of neutral lipids (triglyceride and cholesterol ester) and an envelope of polar lipids (phospholipids and non-esterified cholesterol). There are 3 different classes of plasma lipoproteins with different core lipid content: the low density lipoprotein (LDL) which is cholesteryl ester (CE) rich; high density lipoprotein (HDL) which is also cholesteryl ester (CE) rich; and the very low density lipoprotein (VLDL) which is triglyceride (TG) rich. The different lipoproteins can be separated based on their different flotation density or size.
High LDL-cholesterol (LDL-C) and triglyceride levels are positively correlated, while high levels of HDL-cholesterol (HDL-C) are negatively correlated with the risk for developing cardiovascular diseases.
No wholly satisfactory HDL-elevating therapies exist. Niacin can significantly increase HDL, but has serious toleration issues which reduce compliance. Fibrates and the HMG CoA reductase inhibitors raise HDL-cholesterol only modestly (10-12%). As a result, there is a significant unmet medical need for a well-tolerated agent which can significantly elevate plasma HDL levels.
Thus, HDL-cholesterol raising agents can be useful as medicaments for the treatment and/or prophylaxis of atherosclerosis, peripheral vascular disease, dyslipidemia, hyperbetalipoproteinemia, hypoalphalipoproteinemia, hypercholesterolemia, hypertriglyceridemia, familial hypercholesterolemia, cardiovascular disorders, angina, ischemia, cardiac ischemia, stroke, myocardial infarction, reperfusion injury, angioplastic restenosis, hypertension, and vascular complications of diabetes, improvement of glycemic control, obesity or endotoxemia.
In addition, HDL-cholesterol raising agents may be used in combination with another compound, said compound being an HMG-CoA reductase inhibitor, an microsomal triglyceride transfer protein (MTP)/ApoB secretion inhibitor, a PPAR activator, a bile acid reuptake inhibitor, a cholesteryl ester transfer protein (CETP) inhibitor, a cholesterol absorption inhibitor, a cholesterol synthesis inhibitor, a fibrate, niacin, preparations containing niacin or other HM74a agonists, an ion-exchange resin, an antioxidant, an ACAT inhibitor or a bile acid sequestrant.
Object of the present invention is therefore to provide compounds that are potent HDL-cholesterol raising agents. It has been found that the compounds of formula I of the present invention are very useful for the treatment and/or prophylaxis of diseases and disorders which can be treated with HDL-cholesterol raising agents, i.e. the compounds of formula I are especially useful for the treatment and/or prevention of dyslipidemia, atherosclerosis and cardiovascular diseases. Object of the present invention is also to provide compounds which are, at therapeutically active concentrations that increase HDL-concentrations, not interacting with the CB1 receptor. This is because CB1 receptor ligands may compromise the therapeutic utility of HDL-cholesterol raising agents, as both agonists and antagonists of the CB1 receptor have the potential to lead to side effects.