The instant invention relates to substituted 2-azetidinones and the pharmaceutically acceptable salts and esters thereof, and to their use alone or in combination with other active agents to treat hypercholesterolemia and for preventing, halting or slowing the progression of atherosclerosis and related conditions and disease events.
It has been clear for several decades that elevated blood cholesterol is a major risk factor for coronary heart disease, and many studies have shown that the risk of CHD events can be reduced by lipid-lowering therapy. Prior to 1987, the lipid-lowering armamentarium was limited essentially to a low saturated fat and cholesterol diet, the bile acid sequestrants (cholestyramine and colestipol), nicotinic acid (niacin), the fibrates and probucol. Unfortunately, all of these treatments have limited efficacy or tolerability, or both. Substantial reductions in LDL (low density lipoprotein) cholesterol accompanied by increases in HDL (high density lipoprotein) cholesterol could be achieved by the combination of a lipid-lowering diet and a bile acid sequestrant, with or without the addition of nicotinic acid. However, this therapy is not easy to administer or tolerate and was therefore often unsuccessful except in specialist lipid clinics. The fibrates produce a moderate reduction in LDL cholesterol accompanied by increased HDL cholesterol and a substantial reduction in triglycerides, and because they are well tolerated these drugs have been more widely used. Probucol produces only a small reduction in LDL cholesterol and also reduces HDL cholesterol, which, because of the strong inverse relationship between HDL cholesterol level and CHD risk, is generally considered undesirable. With the introduction of lovastatin, the first inhibitor of HMG-CoA reductase to become available for prescription in 1987, for the first time physicians were able to obtain large reductions in plasma cholesterol with very few adverse effects.
Recent studies have unequivocally demonstrated that lovastatin, simvastatin and pravastatin, all members of the HMG-CoA reductase inhibitor class, slow the progression of atherosclerotic lesions in the coronary and carotid arteries. Simvastatin and pravastatin have also been shown to reduce the risk of coronary heart disease events, and in the case of simvastatin a highly significant reduction in the risk of coronary death and total mortality has been shown by the Scandinavian Simvastatin Survival Study. This study also provided some evidence for a reduction in cerebrovascular events. Despite the substantial reduction in the risk of coronary morbidity and mortality achieved by simvastatin, the risk is still substantial in the treated patients. For example, in the Scandinavian Simvastatin Survival Study, the 42% reduction in the risk of coronary death still left 5% of the treated patients to die of their disease over the course of this 5 year study. Further reduction of risk is clearly needed.
A more recent class of anti-hyperlipidemic agents that has emerged includes inhibitors of cholesterol absorption. Ezetimibe, the first compound to receive regulatory approval in this class, is currently marketed in the U.S. under the tradename ZETIA®. Ezetimibe has the following chemical structure and is described in U.S. Pat. Nos. Re. 37721 and 5,846,966:

Sugar-substituted 2-azetidinones, including glucuronidated analogs of the following general structure:
and methods for making them are disclosed in U.S. Pat. No. 5,756,470, wherein Ar1 and Ar2 are unsubstituted or substituted aryl groups.
Additional cholesterol absorption inhibitors are described in WO2002/066464 A1 (applied for by Kotobuki Pharmaceutical Co.), and U.S. 2002/0137689 A1 (Glombik et al.). WO2002/066464 A1 discloses hypolipidemic compounds of general formula
wherein, among other definitions, A1, A3 and A4 can be
and wherein R2 is —CH2OH, —CH2OC(O)—R1, or —CO2R1; R3 is —OH or —OC(O)R1, and R4 is —(CH2)kR5(CH2)i— where k and i are zero or integers of one or more, and k+i is an integer of 10 or less; and R5 is a single bond, —CH═CH—, —OCH2—, carbonyl or —CH(OH).
U.S. 2002/0137689 A1 discloses hypolipidemic compounds of general formula
wherein, among other definitions, R1, R2, R3, R4, R5, R6 independently of one another can be (C0-C30)-alkylene-(LAG), where one or more carbon atoms of the alkylene radical may be replaced by —O—, —(C═O)—, —CH═CH—, —C≡C—, —N((C1-C6)-alkyl)-, —N((C1-C6)-alkylphenyl) or —NH—; and (LAG) is a sugar residue, disugar residue, trisugar residue, tetrasugar residue; a sugar acid, or an amino sugar.
In the ongoing effort to discover novel treatments for hyperlipidemia and atherosclerotic process, the instant invention provides novel cholesterol absorption inhibitors, described below.