| Pharmacotherapeutic group: Other lipid modifying agents. ATC code: C10A X09'Ezetrol' is in a new class of lipid-lowering compounds that selectively inhibit the intestinal absorption of cholesterol and related plant sterols. 'Ezetrol' is orally active, and has a mechanism of action that differs from other classes of cholesterol reducing compounds (e.g. statins, bile acid sequestrants [resins], fibric acid derivatives, and plant stanols). The molecular target of ezetimibe is the sterol transporter, Niemann-Pick C1-Like 1 (NPC1L1), which is responsible for the intestinal uptake of cholesterol and phytosterols.Ezetimibe localises at the brush border of the small intestine and inhibits the absorption of cholesterol, leading to a decrease in the delivery of intestinal cholesterol to the liver; statins reduce cholesterol synthesis in the liver and together these distinct mechanisms provide complementary cholesterol reduction. In a 2 week clinical study in 18 hypercholesterolaemic patients, 'Ezetrol' inhibited intestinal cholesterol absorption by 54%, compared with placebo.A series of preclinical studies was performed to determine the selectivity of ezetimibe for inhibiting cholesterol absorption. Ezetimibe inhibited the absorption of [14C]-cholesterol with no effect on the absorption of triglycerides, fatty acids, bile acids, progesterone, ethinyl estradiol, or fat soluble vitamins A and D.Epidemiologic studies have established that cardiovascular morbidity and mortality vary directly with the level of total C and LDL C and inversely with the level of HDL C. A beneficial effect of 'Ezetrol' on cardiovascular morbidity and mortality has not yet been demonstrated.CLINICAL TRIALS In controlled clinical studies, 'Ezetrol', either as monotherapy or co-administered with a statin significantly reduced total cholesterol (total C), low-density lipoprotein cholesterol (LDL C), apolipoprotein B (Apo B), and trigylcerides (TG) and increased high-density lipoprotein cholesterol (HDL C) in patients with hypercholesterolaemia.Primary hypercholesterolaemia In a double-blind, placebo-controlled, 8-week study, 769 patients with hypercholesterolaemia already receiving statin monotherapy and not at National Cholesterol Education Program (NCEP) LDL C goal (2.6 to 4.1 mmol/l [100 to 160 mg/dl], depending on baseline characteristics) were randomised to receive either 'Ezetrol' 10 mg or placebo in addition to their on-going statin therapy.Among statin-treated patients not at LDL C goal at baseline (~82%), significantly more patients randomised to 'Ezetrol' achieved their LDL C goal at study endpoint compared to patients randomised to placebo, 72% and 19% respectively. The corresponding LDL-C reductions were significantly different (25% and 4% for 'Ezetrol' versus placebo, respectively). In addition, 'Ezetrol', added to on-going statin therapy, significantly decreased total-C, Apo B, TG and increased HDL-C, compared with placebo. 'Ezetrol' or placebo added to statin therapy reduced median C reactive protein by 10% or 0% from baseline, respectively.In two, double-blind, randomised placebo-controlled, 12-week studies in 1,719 patients with primary hypercholesterolaemia, 'Ezetrol' 10 mg significantly lowered total C (13%), LDL C (19%), Apo B (14%), and TG (8%) and increased HDL C (3%) compared to placebo. In addition, 'Ezetrol' had no effect on the plasma concentrations of the fat-soluble vitamins A, D, and E, no effect on prothrombin time, and, like other lipid-lowering agents, did not impair adrenocortical steroid hormone production.Homozygous Familial Hypercholesterolaemia (HoFH) A double blind, randomised, 12 week study enrolled 50 patients with a clinical and/or genotypic diagnosis of HoFH, who were receiving atorvastatin or simvastatin (40 mg) with or without concomitant LDL apheresis. 'Ezetrol' co-administered with atorvastatin (40 or 80 mg) or simvastatin (40 or 80 mg), significantly reduced LDL C by 15% compared with increasing the dose of simvastatin or atorvastatin monotherapy from 40 to 80 mg.Homozygous sitosterolaemia (phytosterolaemia) In a double-blind, placebo-controlled, 8-week trial, 37 patients with homozygous sitosterolaemia were randomised to receive 'Ezetrol' 10 mg (n=30) or placebo (n=7). Some patients were receiving other treatments (e.g. statins, resins). 'Ezetrol' significantly lowered the two major plant sterols, sitosterol and campesterol, by 21% and 24% from baseline, respectively. The effects of decreasing sitosterol on morbidity and mortality in this population are not known. | |