Ezetimibe-Simvastatin (Vytorin)
Ezetimibe 10 mg / Simvastatin 10, 20, 40, or 80 mg fixed-dose combination
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Primary hyperlipidaemia or mixed hyperlipidaemia | Adults | Adjunctive to diet; dual-mechanism LDL-C, TG, and HDL-C improvement | FDA Approved |
| Heterozygous familial hypercholesterolaemia (HeFH) | Adults and paediatric patients ≥10 years | Adjunctive to diet | FDA Approved |
| Homozygous familial hypercholesterolaemia (HoFH) | Adults | Adjunct to other lipid-lowering treatments | FDA Approved |
| CV risk reduction (simvastatin component) | Adults with established CHD, CVD, PVD, and/or diabetes | Reduces total mortality, CHD death, MI, stroke, and revascularisation | FDA Approved |
Ezetimibe-simvastatin was FDA-approved in 2004, combining a cholesterol absorption inhibitor with a statin in a single tablet. The IMPROVE-IT trial (NEJM 2015) demonstrated that adding ezetimibe 10 mg to simvastatin 40 mg reduced major adverse cardiovascular events by 6.4% (HR 0.936, P=0.016) in 18,144 post-ACS patients over a median 6 years, providing the first evidence that a nonstatin agent improves CV outcomes when added to statin therapy. The 2018 AHA/ACC cholesterol guideline recommends ezetimibe as first-line add-on therapy for patients not at LDL-C goal on maximally tolerated statin. The maximum recommended dosage is 10/40 mg daily; the 10/80 mg dose is restricted to patients already tolerating it for ≥12 months without muscle toxicity.
The FDA PI states: “No incremental benefit of Vytorin on cardiovascular morbidity and mortality over and above that demonstrated for simvastatin has been established.” However, the IMPROVE-IT trial (using the same drug components) demonstrated CV outcome benefit with ezetimibe added to simvastatin 40 mg. The AHA/ACC guideline endorses ezetimibe add-on therapy based on IMPROVE-IT data.
Dosing
Adult Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Primary hyperlipidaemia — standard initiation | 10/10 or 10/20 mg once daily | 10/20–10/40 mg once daily | 10/40 mg/day | Take in the evening, with or without food Assess LDL-C as early as 4 weeks; near-maximal response within 2 weeks |
| Post-ACS CV risk reduction (IMPROVE-IT protocol) | 10/40 mg once daily | 10/40 mg once daily | 10/40 mg/day | Simvastatin 40 mg is moderate-intensity IMPROVE-IT: median LDL-C 53.7 mg/dL achieved; HR 0.936 for MACE (P=0.016) |
| Co-administration with verapamil, diltiazem, or dronedarone | 10/10 mg once daily | 10/10 mg once daily | 10/10 mg/day | Simvastatin cap at 10 mg due to increased myopathy risk (FDA PI) |
| Co-administration with amiodarone, amlodipine, or ranolazine | 10/10 mg once daily | 10/10–10/20 mg once daily | 10/20 mg/day | Simvastatin cap at 20 mg due to increased myopathy risk (FDA PI) |
| Moderate-to-severe renal impairment | 10/10 mg once daily | 10/10–10/20 mg once daily | 10/20 mg/day | Doses exceeding 10/20 mg should be used with caution and close monitoring SHARP used 10/20 mg in CKD patients (median eGFR 25.6 mL/min) |
| HoFH — adjunct to other LDL-lowering therapies | 10/40 mg once daily | 10/40 mg once daily | 10/40 mg/day | As adjunct to LDL apheresis and/or other therapies In HoFH trial, ezetimibe + statin reduced LDL-C 21% vs statin dose-doubling (7%) |
| Co-administration with bile acid sequestrant | Per clinical scenario | Per clinical scenario | 10/40 mg/day | Take Vytorin ≥2 hours before or ≥4 hours after bile acid sequestrant Cholestyramine decreases ezetimibe AUC by ~55% |
Paediatric Dosing (HeFH, ≥10 years)
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Heterozygous familial hypercholesterolaemia | 10/10 mg once daily | 10/10–10/40 mg once daily | 10/40 mg/day | Take in the evening Ezetimibe + simvastatin at doses >40 mg not studied in adolescents; not studied in patients <10 years or pre-menarchal girls |
The 10/80 mg dose is restricted to adult patients who have been taking it chronically (e.g., for 12 months or more) without evidence of muscle toxicity. Patients who cannot achieve their LDL-C goal on 10/40 mg should be placed on alternative LDL-C-lowering treatment rather than titrated to 10/80 mg. In a clinical trial of 12,064 simvastatin-treated patients, myopathy incidence was approximately 0.02% at 20 mg/day versus 0.9% at 80 mg/day, and rhabdomyolysis was ~0% versus 0.4% respectively (FDA PI).
Pharmacology
Mechanism of Action
Vytorin combines two complementary mechanisms of cholesterol reduction. Ezetimibe selectively inhibits the Niemann-Pick C1-Like 1 (NPC1L1) transporter at the intestinal brush border, reducing absorption of dietary and biliary cholesterol. Simvastatin is a prodrug (inactive lactone) that is hydrolysed to simvastatin acid, which competitively inhibits HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol biosynthesis. By simultaneously blocking intestinal cholesterol absorption and hepatic cholesterol synthesis, the combination produces greater LDL-C lowering than either agent alone. This dual inhibition also reduces total cholesterol, apolipoprotein B, triglycerides, and non-HDL-C while increasing HDL-C.
ADME Profile
| Parameter | Ezetimibe | Simvastatin |
|---|---|---|
| Absorption | Rapidly absorbed; Tmax 4–12 h (parent), 1–2 h (glucuronide); food does not affect bioavailability | Prodrug (lactone); Tmax 1.3–2.4 h for simvastatin acid; food does not affect absorption |
| Distribution | Protein binding >90%; enterohepatic recycling | Protein binding ~95%; extensive first-pass hepatic extraction |
| Metabolism | UGT glucuronidation in intestine and liver to active ezetimibe-glucuronide (80–90% of circulating drug); does not induce CYP450 | CYP3A4 (major) — basis for all simvastatin dose-cap interactions; active metabolites include simvastatin acid and 6′-hydroxymethyl derivative |
| Elimination | t½ ~22 h; ezetimibe excreted primarily in faeces; glucuronide primarily in urine | t½ ~1.9 h (simvastatin acid); 60% faeces, 13% urine |
No clinically significant pharmacokinetic interaction has been observed between ezetimibe and simvastatin when co-administered. Each component retains its individual PK profile in the combination tablet. The critical interaction concern with Vytorin is from simvastatin’s CYP3A4 metabolism, not from ezetimibe.
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Headache | 5.8% | Most commonly reported adverse reaction; usually transient |
| Increased ALT | 3.7% | Monitor liver enzymes; most common cause of discontinuation (0.9%) |
| Myalgia | 3.6% | Second most common cause of discontinuation (0.6%); assess for myopathy |
| Upper respiratory tract infection | 3.6% | Not clearly drug-related |
| Diarrhoea | 2.8% | Usually mild and self-limiting |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Myopathy / Rhabdomyolysis | CK >10× ULN: 0.2%; risk ~0.9% at simvastatin 80 mg vs ~0.02% at 20 mg | Weeks to months; dose-dependent | Discontinue immediately; check CK and renal function; do NOT use 10/80 mg dose in new patients; rare fatalities reported |
| Hepatotoxicity (transaminase ≥3× ULN) | ~1.3% (ezetimibe+statin) vs 0.4% (statin alone) | Variable | Perform liver enzymes as clinically indicated; discontinue if ≥3× ULN persists; generally asymptomatic and reversible |
| Immune-mediated necrotising myopathy (IMNM) | Very rare (post-marketing, statin class effect) | Months to years; may persist after discontinuation | Discontinue; anti-HMG-CoA reductase antibody testing; rheumatology referral; may require immunosuppression |
| New-onset diabetes mellitus | Uncommon (statin class effect) | Months to years | Continue statin (CV benefit outweighs risk); manage per diabetes guidelines; HbA1c/fasting glucose elevations reported |
| Hypersensitivity reactions | Rare (post-marketing) | Variable | Discontinue permanently; emergency care for anaphylaxis/angioedema |
In a clinical trial, the incidence of myopathy was higher in Chinese patients taking simvastatin 40 mg or ezetimibe/simvastatin 10/40 mg co-administered with lipid-modifying doses (≥1 g/day) of niacin-containing products. This combination should be used with particular caution in Chinese patients.
Drug Interactions
The drug interaction profile of ezetimibe-simvastatin is driven almost entirely by simvastatin’s CYP3A4 metabolism. Ezetimibe itself has a very low interaction potential (metabolised by UGT, does not inhibit or induce CYP450). Drugs that inhibit CYP3A4 increase simvastatin levels and dramatically raise myopathy risk. All simvastatin dose caps in Vytorin apply to the simvastatin component specifically.
Monitoring
- Lipid PanelBaseline, as early as 4 weeks, then periodically
RoutineNear-maximal response within 2 weeks. Assess whether LDL-C goal is achieved. If 10/40 mg insufficient, switch to alternative therapy rather than increasing to 10/80 mg. - Liver Enzymes (ALT/AST)Before initiation; as clinically indicated
RoutineConsecutive transaminase ≥3× ULN occurred in 1.3% (Vytorin) vs 0.4% (statin alone). Generally asymptomatic and reversible. Consider discontinuation if elevations persist. - Creatine Kinase (CK)When clinically indicated (muscle symptoms)
Trigger-basedCK >10× ULN: 0.2% in trials. Higher myopathy risk at simvastatin 80 mg (~0.9%) vs 20 mg (~0.02%). Measure CK for unexplained muscle pain, tenderness, or weakness. - INR (with warfarin)Before initiation; during dose changes
Trigger-basedSimvastatin may modestly potentiate anticoagulant effect. Obtain INR before initiating Vytorin and monitor during dose adjustments. - Digoxin LevelsDuring Vytorin initiation
Trigger-basedSimvastatin may slightly increase digoxin levels. Monitor digoxin trough when starting or adjusting Vytorin. - HbA1c / Fasting GlucosePeriodically in at-risk patients
RoutineHbA1c and fasting glucose elevations reported with statins (class effect). Monitor for new-onset diabetes in patients with metabolic risk factors.
Contraindications & Cautions
Absolute Contraindications
- Concomitant use of strong CYP3A4 inhibitors (itraconazole, ketoconazole, posaconazole, voriconazole, clarithromycin, erythromycin, HIV protease inhibitors, boceprevir, telaprevir, nefazodone, cobicistat-containing products)
- Concomitant use of cyclosporine, danazol, or gemfibrozil
- Acute liver failure or decompensated cirrhosis
- Hypersensitivity to ezetimibe, simvastatin, or any excipient
Relative Contraindications (Specialist Input Recommended)
- Moderate-to-severe hepatic impairment — ezetimibe AUC increases 3–4-fold in Child-Pugh B/C; not recommended
- History of statin-associated myopathy or IMNM
- Moderate-to-severe renal impairment at doses >10/20 mg — use with caution and close monitoring
Use with Caution
- Pregnancy — may cause fetal harm based on mechanism of action; most patients should discontinue when pregnancy recognised; FDA removed the formal contraindication in July 2021, allowing use in very high-risk patients (e.g., HoFH, prior MI/stroke) when benefit outweighs risk
- Breastfeeding — not recommended; simvastatin may pass into breast milk; patients requiring ongoing therapy should use infant formula alternatives
- Elderly patients (≥65 years) — predisposing factor for myopathy
- Uncontrolled hypothyroidism — correct before starting therapy
- Chinese patients taking niacin ≥1 g/day — higher myopathy risk documented in clinical trial
- Co-administration with fibrates (other than gemfibrozil, which is contraindicated) — fenofibrate may be used with caution; assess for cholelithiasis
- Substantial alcohol consumption — hepatotoxicity risk
The risk of myopathy, including rhabdomyolysis, increases with higher simvastatin doses. In a trial of 12,064 patients, the incidence of myopathy was approximately 0.02% with simvastatin 20 mg/day and 0.9% with simvastatin 80 mg/day. Rhabdomyolysis incidence was approximately 0% and 0.4% respectively. The 10/80 mg dose of Vytorin is restricted to patients who have been taking it for ≥12 months without muscle toxicity. Patients unable to reach LDL-C goals on 10/40 mg should be switched to alternative LDL-C-lowering treatment rather than titrated to 10/80 mg.
Patient Counselling
Purpose of Therapy
This medicine combines two different cholesterol-lowering agents in one tablet. One ingredient (ezetimibe) blocks cholesterol from being absorbed from the food you eat, while the other (simvastatin) reduces cholesterol production in the liver. Together, they provide greater cholesterol-lowering than either agent alone. In a large clinical trial, this combination reduced the risk of heart attack and stroke in patients who had already experienced a cardiac event.
How to Take
Take one tablet once daily in the evening, with or without food. Take it at the same time each day. If you also take a bile acid resin (such as cholestyramine), take Vytorin at least 2 hours before or 4 hours after. If you miss a dose, take it as soon as you remember; do not double the next dose. Avoid large quantities of grapefruit juice while taking this medicine.
Sources
- VYTORIN (ezetimibe and simvastatin) tablets — Full Prescribing Information. Organon LLC. Revised 2024. FDA Label (2024)Primary reference for dosing, dose caps, CYP3A4 interactions, adverse reactions, 10/80 mg restriction, and contraindications.
- VYTORIN (ezetimibe and simvastatin) tablets — Full Prescribing Information. Merck/Schering-Plough. 2014. FDA Label (2014)Earlier label version with detailed SHARP safety data and Chinese patient niacin myopathy warning.
- Cannon CP, Blazing MA, Giugliano RP, et al. Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes (IMPROVE-IT). N Engl J Med. 2015;372(25):2387-2397. doi:10.1056/NEJMoa1410489Landmark 18,144-patient RCT demonstrating 6.4% relative MACE reduction (HR 0.936, P=0.016) with ezetimibe/simvastatin 10/40 mg vs simvastatin 40 mg alone post-ACS over median 6 years.
- Murphy SA, Cannon CP, Blazing MA, et al. Reduction in Total Cardiovascular Events With Ezetimibe/Simvastatin Post-Acute Coronary Syndrome. J Am Coll Cardiol. 2016;67(4):353-361. doi:10.1016/j.jacc.2015.10.077IMPROVE-IT total events analysis showing 9% reduction in total (first + recurrent) CV events with ezetimibe/simvastatin.
- Baigent C, Landray MJ, Reith C, et al. The effects of lowering LDL cholesterol with simvastatin plus ezetimibe in patients with chronic kidney disease (SHARP). Lancet. 2011;377(9784):2181-2192. doi:10.1016/S0140-6736(11)60739-39,270-patient RCT showing ezetimibe/simvastatin 10/20 mg reduced major atherosclerotic events by 17% in CKD (median follow-up 4.9 years); confirmed long-term safety in renal impairment.
- Kastelein JJP, Akdim F, Stroes ESG, et al. Simvastatin with or without ezetimibe in familial hypercholesterolemia (ENHANCE). N Engl J Med. 2008;358(14):1431-1443. doi:10.1056/NEJMoa0800742HeFH trial showing greater LDL-C reduction but no carotid IMT difference; initial uncertainty resolved by IMPROVE-IT outcomes data.
- Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol. J Am Coll Cardiol. 2019;73(24):e285-e350. doi:10.1016/j.jacc.2018.11.003Current US cholesterol guideline recommending ezetimibe as first-line nonstatin add-on therapy based on IMPROVE-IT data.
- Lloyd-Jones DM, Morris PB, Ballantyne CM, et al. 2022 ACC Expert Consensus Decision Pathway on the Role of Nonstatin Therapies. J Am Coll Cardiol. 2022;80(14):1366-1418. doi:10.1016/j.jacc.2022.07.006ACC nonstatin pathway positioning ezetimibe as first step after maximally tolerated statin, before PCSK9 inhibitors.
- Altmann SW, Davis HR Jr, Zhu LJ, et al. Niemann-Pick C1 Like 1 protein is critical for intestinal cholesterol absorption. Science. 2004;303(5661):1201-1204. doi:10.1126/science.1093131Seminal study identifying NPC1L1 as the molecular target of ezetimibe.
- Jarcho JA, Keaney JF Jr. Proof That Lower Is Better — LDL Cholesterol and IMPROVE-IT. N Engl J Med. 2015;372(25):2448-2450. doi:10.1056/NEJMe1507041Editorial discussing IMPROVE-IT as evidence supporting the LDL hypothesis that lower is better regardless of mechanism.
- Kosoglou T, Statkevich P, Johnson-Levonas AO, et al. Ezetimibe: a review of its metabolism, pharmacokinetics and drug interactions. Clin Pharmacokinet. 2005;44(5):467-494. doi:10.2165/00003088-200544050-00002Comprehensive PK review of ezetimibe detailing glucuronidation pathway, enterohepatic recycling, and drug interaction studies.
- Wilke RA, Ramsey LB, Johnson SG, et al. The Clinical Pharmacogenomics Implementation Consortium: CPIC Guideline for SLCO1B1 and Simvastatin-Induced Myopathy. Clin Pharmacol Ther. 2012;92(1):112-117. doi:10.1038/clpt.2012.57CPIC guideline on SLCO1B1 pharmacogenomics and simvastatin myopathy risk, recommending lower doses or alternative statins for carriers of the *5 allele.