Simvastatin plus ezetimibe: combination therapy for the management of dyslipidaemia

Hyperlipidaemia is a pivotal risk factor for the development of atherosclerotic disease. A large number of studies have demonstrated that the treatment of abnormalities in lipoprotein levels reduces the risk for myocardial infarction, peripheral vascular disease, carotid artery disease, stroke, and cardiovascular mortality. Despite the development of multiple drug classes to treat dyslipidaemias and the promulgation of clearly defined guidelines for the management of lipid disorders, dyslipidaemia tends to be undertreated in the majority of patients at risk for cardiovascular disease. A part of the reluctance to treat different lipoprotein fractions to goal levels is attributable to physician- and patient-related concerns over the increasing toxicity of available therapies, as their dosages are increased. The risks of hepatotoxicity, myalgia, and rhabdomyolysis are fairly well characterised in patients receiving statins, fibrates and niacin. Another issue affecting treatment success rates is the fact that many patients with complex dyslipidaemias are inadequately responsive to single-agent therapy. As the epidemics of obesity, metabolic syndrome and diabetes mellitus continue to worsen, physicians will encounter severe, mixed dyslipidaemias more frequently. Many of these patients will require combinations of drugs to address the various metabolic derangements causing changes in multiple lipoprotein fractions. Although the need for combination therapy is well-established in the management of disorders, such as hypertension and diabetes, it is less often used for the treatment of dyslipidaemias. The development of safe, cost-effective, and efficacious combination dyslipidaemic therapy is an important goal in cardiovascular medicine. Simvastatin plus ezetimibe has recently been combined as a fixed dose therapy, which offers clinicians the opportunity to simultaneously inhibit two key pathways in cholesterol metabolism: hepatic cholesterol biosynthesis and the absorption of cholesterol at the level of the proximal jejunum. This dual mechanism of inhibition substantially increases the capacity to decrease serum levels of atherogenic low-density lipoproteins and increase high-density lipoprotein, compared with that observed when either drug is used alone. This combination increases the likelihood of therapeutic success in patients with dyslipidaemia.