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Pharmacology: Pharmacodynamics: Mechanism of Action: ATOZET: Plasma cholesterol is derived from intestinal absorption and endogenous synthesis. ATOZET contains ezetimibe and atorvastatin, two lipid-lowering compounds with complementary mechanisms of action. ATOZET reduces elevated total-C, LDL-C, Apo B, TG, and non-HDL-C, and increases HDL-C through dual inhibition of cholesterol absorption and synthesis.
Ezetimibe: Ezetimibe inhibits the intestinal absorption of cholesterol. Ezetimibe 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 localizes 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 hypercholesterolemic patients, ezetimibe 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 the fat-soluble vitamins A and D.
Atorvastatin: Atorvastatin is a selective, competitive inhibitor of HMG-CoA reductase, the rate-limiting enzyme that converts 3-hydroxy-3-methyl-glutaryl-coenzyme A to mevalonate, a precursor of sterols, including cholesterol.
In animal models, atorvastatin lowers plasma cholesterol and lipoprotein levels by inhibiting HMG-CoA reductase and cholesterol synthesis in the liver and by increasing the number of hepatic LDL receptors on the cell surface to enhance uptake and catabolism of LDL; atorvastatin also reduces LDL production and the number of LDL particles.
Clinical Studies: In controlled clinical studies, ATOZET significantly reduced total-C, LDL-C, Apo B, and TG, and increased HDL-C in patients with hypercholesterolaemia.
Primary Hypercholesterolaemia: In a placebo-controlled study, 628 patients with hyperlipidaemia were randomized to receive placebo, ezetimibe (10 mg), atorvastatin (10 mg, 20 mg, 40 mg, or 80 mg), or coadministered ezetimibe and atorvastatin equivalent to ATOZET (10/10, 10/20, 10/40, and 10/80) for up to 12 weeks.
Patients receiving all doses of ATOZET were compared to those receiving all doses of atorvastatin.
ATOZET lowered total-C, LDL-C, Apo B, TG, and non-HDL-C, and increased HDL-C significantly more than atorvastatin alone. (See Table 1.)
Click on icon to see table/diagram/imageIn a controlled study, the Titration of Atorvastatin Versus Ezetimibe Add-On to Atorvastatin in Patients with Hypercholesterolaemia (TEMPO) study, 184 patients, with an LDL-C level ≥2.6 mmol/L and ≤4.1 mmol/L and at moderate high risk for CHD, received atorvastatin 20 mg for a minimum of 4 weeks prior to randomization. Patients not at an LDL-C level <2.6 mmol/L were randomized to receive either coadministered ezetimibe and atorvastatin (equivalent to ATOZET 10/20) or atorvastatin 40 mg for 6 weeks.
ATOZET 10/20 was significantly more effective than doubling the dose of atorvastatin to 40 mg in further reducing total-C (-20% vs. -7%), LDL-C (-31% vs. -11%), Apo B (-21% vs. -8%), and non-HDLC (-27% vs. -10%). Results for HDL-C and TG between the two treatment groups were not significantly different. Also, significantly more patients receiving ATOZET 10/20 attained LDL-C <2.6 mmol/L compared to those receiving atorvastatin 40 mg, 84% vs. 49%.
In a controlled study, The Ezetimibe Plus Atorvastatin Versus Atorvastatin Titration in Achieving Lower LDL-C Targets in Hypercholesterolaemic Patients (EZ-PATH) study, 556 high-cardiovascular-risk patients with a LDL-C level ≥1.8 mmol/L and ≤4.1 mmol/L received atorvastatin 40 mg for a minimum of 4 weeks prior to randomization. Patients not at a LDL-C level <1.8 mmol/L were randomized to receive either coadministered ezetimibe and atorvastatin (equivalent to ATOZET 10/40) or atorvastatin 80 mg for 6 weeks.
ATOZET 10/40 was significantly more effective than doubling the dose of atorvastatin to 80 mg in further reducing total-C (-17% vs. -7%), LDL-C (-27% vs. -11%), Apo B (-18% vs. -8%), TG (-12% vs. -6%), and non-HDL-C (-23% vs. -9%). Results for HDL-C between the two treatment groups were not significantly different. Also, significantly more patients receiving ATOZET 10/40 attained LDL-C <1.8 mmol/L compared to those receiving atorvastatin 80 mg, 74% vs. 32%.
In a placebo-controlled, 8-week study, 308 hypercholesterolemic patients receiving atorvastatin and not at National Cholesterol Education Program (NCEP) LDL-C goal (LDL-C goal based upon baseline LDL-C and CHD risk status) were randomized to receive either ezetimibe 10 mg or placebo in addition to their on-going atorvastatin therapy.
Among patients not at LDL-C goal at baseline (~83%), significantly more patients receiving ezetimibe coadministered with atorvastatin achieved their LDL-C goal compared to patients receiving placebo coadministered with atorvastatin, 67% vs. 19%. Ezetimibe added to atorvastatin therapy lowered LDL-C significantly more than placebo added to atorvastatin therapy, 25% vs. 4%. Ezetimibe added to atorvastatin therapy also significantly decreased total-C, Apo B, and TG compared with placebo added to atorvastatin therapy.
In a controlled, 12-week, 2-phase study, 1539 high-cardiovascular-risk patients, with a LDL-C level between 2.6 and 4.1 mmol/L, on atorvastatin 10 mg daily were randomized to receive: atorvastatin 20 mg, rosuvastatin 10 mg, or ATOZET 10/10. After 6 weeks of treatment (Phase I), patients taking atorvastatin 20 mg who failed to achieve a LDL-C level <2.6 mmol/L were switched to either atorvastatin 40 mg or ATOZET 10/20 for 6 weeks (Phase II), and similar patients taking rosuvastatin 10 mg during Phase I were switched to either rosuvastatin 20 mg or ATOZET 10/20. Reductions in LDL-C and comparisons between the ATOZET group and other treatment groups studied are shown in Table 2. (See Table 2.)
Click on icon to see table/diagram/imageTable 2 does not contain data comparing the effects of ATOZET 10/10 or 10/20 to doses higher than atorvastatin 40 mg or rosuvastatin 20 mg.
In a placebo-controlled study, the Myocardial Ischaemia Reduction with Aggressive Cholesterol Lowering (MIRACL) study, patients with an acute coronary syndrome (non Q-wave MI or unstable angina) were randomized to receive atorvastatin 80 mg/day (n=1538) or placebo (n=1548). Treatment was initiated during the acute phase after hospital admission and lasted for 16 weeks. Atorvastatin 80 mg/day provided a 16% (p=0.048) reduction in risk of the combined primary endpoint: death from any cause, nonfatal MI, resuscitated cardiac arrest, or angina pectoris with evidence of myocardial ischaemia requiring hospitalisation. This was mainly due to a 26% reduction in re-hospitalisation for angina pectoris with evidence of myocardial ischaemia (p=0.018).
ATOZET contains atorvastatin. In a placebo-controlled study, the Anglo-Scandinavian Cardiac Outcomes Trial Lipid Lowering Arm (ASCOT-LLA), the effect of atorvastatin 10 mg on fatal and non-fatal CHD was assessed in 10,305 hypertensive patients, 40-80 years old, with TC levels ≤6.5 mmol/L and at least three cardiovascular risk factors. Patients were followed for a median duration of 3.3 years. Atorvastatin 10 mg significantly (p<0.001) reduced the relative risk for: fatal CHD plus nonfatal MI by 36% (absolute risk reduction=1.1%); total cardiovascular events and revascularization procedures by 20% (absolute risk reduction=1.9%); and total coronary events by 29% (absolute risk reduction=1.4%).
In a placebo-controlled study, the Collaborative Atorvastatin Diabetes Study (CARDS), the effect of atorvastatin 10 mg on cardiovascular disease (CVD) endpoints was assessed in 2838 patients, 40-75 years old, with type 2 diabetes, one or more cardiovascular risk factors, LDL ≤4.1 mmol/L, and TG ≤6.8 mmol/L. Patients were followed for a median duration of 3.9 years. Atorvastatin 10 mg significantly (p<0.05) reduced: the rate of major cardiovascular events by 37% (absolute risk reduction=3.2%); the risk of stroke by 48% (absolute risk reduction=1.3%); and the risk of MI by 42% (absolute risk reduction=1.9%).
ATOZET: Prevention of Cardiovascular Events: In an ezetimibe/simvastatin, multicenter, randomized, double-blind, active-control study, 18,144 patients enrolled within 10 days of hospitalisation for acute coronary syndrome (ACS; either acute myocardial infarction [MI] or unstable angina [UA]). All patients were randomized in a 1:1 ratio to receive either ezetimibe/simvastatin 10/40 mg (n=9067) or simvastatin 40 mg (n=9077) and followed for a median of 6.0 years.
Patients had a mean age of 63.6 years; 76% were male, 84% were Caucasian, and 27% were diabetic. The average LDL-C value at the time of study qualifying event was 80 mg/dL (2.1 mmol/L) for those on lipid-lowering therapy (n=6390) and 101 mg/dL (2.6 mmol/L) for those not on previous lipid-lowering therapy (n=11594). Prior to the hospitalisation for the qualifying ACS event, 34% of the patients were on statin therapy. At one-year, the average LDL-C for patients continuing on therapy was 53.2 mg/dL (1.4 mmol/L) for the ezetimibe/simvastatin group and 69.9 mg/dL (1.8 mmol/L) for the simvastatin monotherapy group.
The primary endpoint was a composite consisting of cardiovascular death, major coronary events (MCE; defined as non-fatal myocardial infarction, documented unstable angina that required hospitalisation, or any coronary revascularization procedure occurring at least 30 days after randomized treatment assignment) and non-fatal stroke. The study demonstrated that treatment with ezetimibe/simvastatin provided incremental benefit in reducing the primary composite endpoint of cardiovascular death, MCE, and non-fatal stroke compared with simvastatin alone (relative risk reduction of 6.4%, p=0.016). The primary endpoint occurred in 2572 of 9067 patients (7-year Kaplan-Meier [KM] rate 32.72%) in the ezetimibe/simvastatin group and 2742 of 9077 patients (7-year KM rate 34.67%) in the simvastatin alone group. (See Figure and Table 3.) This incremental benefit is expected to be similar with coadministration of ezetimibe and atorvastatin. Total mortality was unchanged in this high risk group.
There was an overall benefit for all strokes; however there was a small non-significant increase in haemorrhagic stroke in the ezetimibe-simvastatin group compared with simvastatin alone. The risk of haemorrhagic stroke for ezetimibe coadministered with higher potency statins in long-term outcome studies has not been evaluated.
The treatment effect of ezetimibe/simvastatin was generally consistent with the overall results across many subgroups, including sex, age, race, medical history of diabetes mellitus, baseline lipid levels, prior statin therapy, prior stroke, and hypertension. (See figure and Table 3.)
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Click on icon to see table/diagram/imageHomozygous Familial Hypercholesterolaemia (HoFH): A double-blind, randomized, 12-week study was performed in patients with a clinical and/or genotypic diagnosis of HoFH. Data were analyzed from a subgroup of patients (n=36) receiving atorvastatin 40 mg at baseline. Increasing the dose of atorvastatin from 40 to 80 mg (n=12) produced a reduction of LDL-C of 2% from baseline on atorvastatin 40 mg. Coadministered ezetimibe and atorvastatin equivalent to ATOZET (10/40 and 10/80 pooled, n=24), produced a reduction of LDL-C of 19% from baseline on atorvastatin 40 mg. In those patients coadministered ezetimibe and atorvastatin equivalent to ATOZET (10/80, n=12), a reduction of LDL-C of 25% from baseline on atorvastatin 40 mg was produced.
After completing the 12-week study, eligible patients (n=35), who were receiving atorvastatin 40 mg at baseline, were assigned to coadministered ezetimibe and atorvastatin equivalent to ATOZET 10/40 for up to an additional 24 months. Following at least 4 weeks of treatment, the atorvastatin dose could be doubled to a maximum dose of 80 mg. At the end of the 24 months, ATOZET (10/40 and 10/80 pooled) produced a reduction of LDL-C that was consistent with that seen in the 12-week study.
Pharmacokinetics: General Introduction: ATOZET: ATOZET has been shown to be bioequivalent to coadministration of corresponding doses of ezetimibe and atorvastatin tablets.
Absorption: ATOZET: The effects of a high-fat meal on the pharmacokinetics of ezetimibe and atorvastatin when administered as ATOZET tablets are comparable to those reported for the individual tablets.
Ezetimibe: After oral administration, ezetimibe is rapidly absorbed and extensively conjugated to a pharmacologically active phenolic glucuronide (ezetimibe-glucuronide). Mean maximum plasma concentrations (Cmax) occur within 1 to 2 hours for ezetimibe-glucuronide and 4 to 12 hours for ezetimibe. The absolute bioavailability of ezetimibe cannot be determined as the compound is virtually insoluble in aqueous media suitable for injection.
Concomitant food administration (high fat or non-fat meals) had no effect on the oral bioavailability of ezetimibe when administered as ezetimibe 10 mg tablets.
Atorvastatin: Atorvastatin is rapidly absorbed after oral administration; maximum plasma concentrations (Cmax) occur within 1 to 2 hours. Extent of absorption increases in proportion to atorvastatin dose. After oral administration, atorvastatin film-coated tablets are 95% to 99% bioavailable compared to the oral solution. The absolute bioavailability of atorvastatin is approximately 12% and the systemic availability of HMG-CoA reductase inhibitory activity is approximately 30%. The low systemic availability is attributed to presystemic clearance in gastrointestinal mucosa and/or hepatic first-pass metabolism.
Distribution: Ezetimibe: Ezetimibe and ezetimibe-glucuronide are bound 99.7% and 88 to 92% to human plasma proteins, respectively.
Atorvastatin: Mean volume of distribution of atorvastatin is approximately 381 l. Atorvastatin is ≥98% bound to plasma proteins.
Metabolism: Ezetimibe: Ezetimibe is metabolized primarily in the small intestine and liver via glucuronide conjugation (a phase II reaction) with subsequent biliary excretion. Minimal oxidative metabolism (a phase I reaction) has been observed in all species evaluated. Ezetimibe and ezetimibe-glucuronide are the major drug-derived compounds detected in plasma, constituting approximately 10 to 20% and 80 to 90% of the total drug in plasma, respectively. Both ezetimibe and ezetimibe-glucuronide are slowly eliminated from plasma with evidence of significant enterohepatic recycling. The half-life for ezetimibe and ezetimibe-glucuronide is approximately 22 hours.
Atorvastatin: Atorvastatin is metabolized by cytochrome P450 3A4 to ortho- and parahydroxylated derivatives and various beta-oxidation products. Apart from other pathways these products are further metabolized via glucuronidation. In vitro, inhibition of HMG-CoA reductase by ortho- and parahydroxylated metabolites is equivalent to that of atorvastatin. Approximately 70% of circulating inhibitory activity for HMG-CoA reductase is attributed to active metabolites.
Elimination: Ezetimibe: Following oral administration of 14C-ezetimibe (20 mg) to human subjects, total ezetimibe accounted for approximately 93% of the total radioactivity in plasma. Approximately 78% and 11% of the administered radioactivity were recovered in the feces and urine, respectively, over a 10-day collection period. After 48 hours, there were no detectable levels of radioactivity in the plasma.
Atorvastatin: Atorvastatin is eliminated primarily in bile following hepatic and/or extrahepatic metabolism. However, the medicinal product does not appear to undergo significant enterohepatic recirculation. Mean plasma elimination half-life of atorvastatin in humans is approximately 14 hours. The half-life of inhibitory activity for HMG-CoA reductase is approximately 20 to 30 hours due to the contribution of active metabolites.
Special Populations: Renal Impairment: Ezetimibe: After a single 10-mg dose of ezetimibe in patients with severe renal disease (n=8; mean CrCl ≤30 ml/min/1.73 m2), the mean AUC for total ezetimibe was increased approximately 1.5-fold, compared to healthy subjects (n=9).
An additional patient in this study (post-renal transplant and receiving multiple medications, including cyclosporine) had a 12-fold greater exposure to total ezetimibe.
Atorvastatin: Renal disease has no influence on the plasma concentrations or lipid effects of atorvastatin and its active metabolites.
Hepatic Impairment: Ezetimibe: After a single 10-mg dose of ezetimibe, the mean area under the curve (AUC) for total ezetimibe was increased approximately 1.7-fold in patients with mild hepatic impairment (Child-Pugh score 5 or 6), compared to healthy subjects. In a 14-day, multiple-dose study (10 mg daily) in patients with moderate hepatic impairment (Child-Pugh score 7 to 9), the mean AUC for total ezetimibe was increased approximately 4-fold on Day 1 and Day 14 compared to healthy subjects. No dosage adjustment is necessary for patients with mild hepatic impairment. Due to the unknown effects of the increased exposure to ezetimibe in patients with moderate or severe (Child-Pugh score >9) hepatic impairment, ezetimibe is not recommended in these patients [see Hepatic Impairment under Precautions].
Atorvastatin: Plasma concentrations of atorvastatin and its active metabolites are markedly increased (approx. 16-fold in Cmax and approx. 11-fold in AUC) in patients with chronic alcoholic liver disease (Child-Pugh B).
Pediatric: Ezetimibe: The absorption and metabolism of ezetimibe are similar between children and adolescents (10 to 18 years) and adults. Based on total ezetimibe, there are no pharmacokinetic differences between adolescents and adults. Pharmacokinetic data in the pediatric population <10 years of age are not available.
Atorvastatin: Apparent oral clearance of atorvastatin in pediatric subjects appeared similar to that of adults when scaled allometrically by body weight as the body weight was the only significant covariate in atorvastatin population PK model with data including pediatric HeFH patients (ages 10 years to 17 years of age, n=29) in an open-label, 8-week study.
Geriatric: Ezetimibe: Plasma concentrations for total ezetimibe are about 2-fold higher in the elderly (≥65 years) than in the young (18 to 45 years). LDL-C reduction and safety profile are comparable between elderly and young subjects treated with ezetimibe.
Atorvastatin: Plasma concentrations of atorvastatin and its active metabolites are higher in healthy elderly subjects than in young adults while the lipid effects were comparable to those seen in younger patient populations.
Race: Based on a meta analysis of pharmacokinetic studies with ezetimibe, there were no pharmacokinetic differences between Blacks and Caucasians.
Gender: Ezetimibe: Plasma concentrations for total ezetimibe are slightly higher (<20%) in women than in men. LDL-C reduction and safety profile are comparable between men and women treated with ezetimibe.
Atorvastatin: Concentrations of atorvastatin and its active metabolites in women differ from those in men (women: approx. 20% higher for Cmax and approx. 10% lower for AUC). These differences were of no clinical significance, resulting in no clinically significant differences in lipid effects among men and women.
Hemodialysis: Atorvastatin: While studies have not been conducted in patients with end-stage renal disease, hemodialysis is not expected to significantly enhance clearance of atorvastatin since the drug is extensively bound to plasma proteins.
