Simvastatin
Brand names: Zocor (tablets), FloLipid (oral suspension)
Quick Facts
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Reduction of total mortality, CHD death, non-fatal MI, stroke, and need for revascularization | Adults with established CHD, cerebrovascular disease, peripheral vascular disease, and/or diabetes who are at high risk of CHD events | Adjunct to diet | FDA Approved |
| Primary hyperlipidemia | Adults | Adjunct to diet | FDA Approved |
| Heterozygous familial hypercholesterolemia (HeFH) | Adults and pediatric patients aged 10 years and older | Adjunct to diet | FDA Approved |
| Homozygous familial hypercholesterolemia (HoFH) | Adults | Adjunct to other LDL-C-lowering therapies (e.g., LDL apheresis, ezetimibe) | FDA Approved |
| Hypertriglyceridemia (Fredrickson type IV) | Adults | Adjunct to diet | FDA Approved |
| Primary dysbetalipoproteinemia (Fredrickson type III) | Adults | Adjunct to diet | FDA Approved |
Simvastatin was the first statin to demonstrate a mortality benefit in a large outcome trial — the 1994 Scandinavian Simvastatin Survival Study (4S) showed a 30% reduction in all-cause mortality and 42% reduction in CHD mortality in patients with established CHD over a median 5.4 years. The Heart Protection Study (HPS) subsequently confirmed cardiovascular benefit across a broader high-risk population (diabetes, peripheral vascular disease, prior stroke) regardless of baseline LDL-C, with a 13% reduction in all-cause mortality and 18% reduction in vascular mortality. The 2018 AHA/ACC Cholesterol Guideline classifies simvastatin 20–40 mg as moderate intensity (LDL-C reduction ~30–49%) and simvastatin 10 mg as low intensity (<30%); no simvastatin dose meets the high-intensity threshold (≥50%) — even 80 mg achieves only ~46% LDL-C reduction in the VOYAGER meta-analysis, and 80 mg is no longer recommended for new initiation due to myopathy risk.
Stroke prevention beyond approved indications — extrapolation from class-wide CTT meta-analyses for patients with high ASCVD risk. Evidence: high quality (extrapolated).
Diabetic dyslipidemia in primary prevention — used as a moderate-intensity option, particularly when cost is a concern; HPS supports benefit. Evidence: moderate quality.
Aortic valve calcification slowing — investigated in SEAS and other trials; the data have not supported a meaningful effect on disease progression. Evidence: low quality (negative trials).
Dosing
All doses are administered orally, once daily, in the evening (cholesterol biosynthesis peaks overnight, so evening dosing maximizes pharmacodynamic effect for short-half-life statins). Reassess LDL-C as early as 4 weeks after initiation or dose change. The maximum recommended dosage is 40 mg/day; the 80 mg dose is restricted to patients who have already tolerated it chronically (≥12 months) without muscle toxicity and is not appropriate for new initiation or up-titration. Note that simvastatin 10 mg is classified as low-intensity therapy by the 2018 AHA/ACC guideline; only 20 mg or higher meets the moderate-intensity threshold.
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Primary hyperlipidemia — moderate-intensity goal (LDL-C reduction 30–49%) | 20 mg evening | 20–40 mg evening | 40 mg/day | 20–40 mg = moderate intensity per AHA/ACC 2018 Per VOYAGER meta-analysis: ~32% LDL-C reduction at 20 mg, ~37% at 40 mg. 10 mg is low intensity (~28% reduction) |
| ASCVD secondary prevention (post-MI, post-stroke, established CAD/PAD, diabetes with high CHD risk) | 40 mg evening | 40 mg evening | 40 mg/day | If <50% LDL-C reduction goal not met at 40 mg, switch to a high-intensity statin (atorvastatin 40–80 or rosuvastatin 20–40) rather than escalate to 80 mg HPS evidence supports 40 mg in this population |
| Heterozygous familial hypercholesterolemia (HeFH) — adults | 20–40 mg evening | 40 mg evening | 40 mg/day | If goal not achieved, add ezetimibe or a PCSK9 inhibitor rather than escalate dose |
| Heterozygous familial hypercholesterolemia (HeFH) — pediatric ≥10 years | 10 mg evening | 10–40 mg evening | 40 mg/day | Adjust at intervals of ≥4 weeks. Doses >40 mg not studied in this population Adolescent females: counsel on contraception |
| Homozygous familial hypercholesterolemia (HoFH) | 40 mg evening | 40 mg evening (80 mg permitted in patients chronically tolerating it without muscle toxicity) | 80 mg/day (restricted use) | Use as adjunct to other LDL-C-lowering therapy (LDL apheresis, ezetimibe, PCSK9 inhibitor, lomitapide) Per FDA label HoFH study (n=12): mean LDL-C reduction 30% (range 14–46%) at 80 mg/day; 14% at 40 mg/day |
| Hypertriglyceridemia / primary dysbetalipoproteinemia | 20 mg evening | 20–40 mg evening | 40 mg/day | Modest TG reduction (~20–30%); consider fenofibrate or icosapent ethyl if TG remain elevated Gemfibrozil is contraindicated |
| Continuation of pre-existing 80 mg dose (legacy patients only) | Not for new initiation | 80 mg evening (only if tolerated ≥12 months without muscle toxicity) | 80 mg/day | Do NOT initiate 80 mg in new patients. Switch to alternate statin if any new interacting drug is started or if myopathy risk emerges FDA restricted 80 mg in 2011 due to myopathy data from SEARCH |
Population-Specific Adjustments
| Population | Starting / Recommended Dose | Maximum Dose | Notes |
|---|---|---|---|
| Severe renal impairment (CrCl <30 mL/min/1.73 m²) | 5 mg evening (use 5 mg generic; Zocor 5 mg no longer marketed) | Cautious titration; close monitoring | Higher plasma concentrations and elevated myopathy risk |
| Chinese ancestry on lipid-modifying niacin (≥1 g/day) | Limit to 20 mg evening | 20 mg/day with niacin | Increased myopathy risk observed in HPS2-THRIVE; do not use 80 mg with niacin in this population |
| Concomitant verapamil, diltiazem, or dronedarone | Standard initiation | 10 mg/day | CYP3A4 inhibition raises myopathy risk substantially |
| Concomitant amiodarone, amlodipine, or ranolazine | Standard initiation | 20 mg/day | Moderate CYP3A4 inhibition; the dose cap was retained after the 2011 FDA review |
| Concomitant lomitapide (HoFH) | Reduce existing dose by 50% | 20 mg/day (or 40 mg if previously chronic 80 mg) | Lomitapide approximately doubles simvastatin exposure |
| Concomitant ticagrelor | Standard initiation | 40 mg/day | Ticagrelor inhibits CYP3A4; do not use higher doses |
| Mild–moderate hepatic impairment | Use cautiously; standard initiation | Standard maxima | Acute liver failure or decompensated cirrhosis warrants alternative therapy |
| Elderly (≥65 years) | Lower starting dose (10 mg) reasonable | Standard maxima | Risk factor for myopathy per the PI; 4S and HPS showed similar efficacy and safety |
Simvastatin has a short half-life (~2 hours) and the active acid metabolite has a similarly short half-life (~2–4 hours). Endogenous cholesterol synthesis is highest during the night, so evening administration synchronises peak drug effect with peak HMG-CoA reductase activity and produces meaningfully greater LDL-C reduction than morning dosing. This timing rule applies to all short-acting statins (lovastatin, simvastatin) and not to long-acting statins (atorvastatin, rosuvastatin), which can be taken any time.
If a patient is not at LDL-C goal on simvastatin 40 mg, the correct move is to switch to a higher-intensity statin (atorvastatin 40–80 mg or rosuvastatin 20–40 mg) or add ezetimibe — not to escalate to simvastatin 80 mg. The 80 mg dose carries roughly 8-fold higher myopathy risk than the 40 mg dose and is reserved for patients already tolerating it long-term. Patients on 80 mg who need to start an interacting drug should be switched to a different statin rather than have the interacting drug added.
Pharmacology
Mechanism of Action
Simvastatin is administered as an inactive lipophilic lactone prodrug that is hydrolysed in the liver — primarily by carboxylesterases and paraoxonases — to its active β-hydroxyacid form, simvastatin acid. The active acid is a competitive, reversible inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme converting HMG-CoA to mevalonate in hepatic cholesterol biosynthesis. Reduced intracellular cholesterol upregulates LDL receptors on hepatocyte surfaces, increasing clearance of LDL particles from circulation. Net effects are dose-dependent reductions in LDL-C (approximately 28–46% across the 10–80 mg dose range per the VOYAGER meta-analysis), apolipoprotein B, non-HDL-C, and total cholesterol, with smaller reductions in triglycerides (~10–30%) and modest increases in HDL-C (~5–15%).
Because simvastatin is a lipophilic statin with extensive first-pass metabolism, it is more vulnerable to CYP3A4-driven drug interactions than the hydrophilic statins (pravastatin, rosuvastatin). Inhibitors of CYP3A4 — strong (azole antifungals, macrolide antibiotics, certain HIV antiretrovirals, cobicistat, nefazodone) or moderate (verapamil, diltiazem, amiodarone, amlodipine, ranolazine, dronedarone, ticagrelor) — substantially raise simvastatin exposure and predictably raise myopathy risk. Simvastatin acid is a substrate of OATP1B1 (encoded by SLCO1B1), which adds a second mechanism for interactions with cyclosporine, gemfibrozil, and similar transporter inhibitors; the SEARCH GWAS identified SLCO1B1 variants as the dominant genetic determinant of simvastatin-induced myopathy.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Tmax ~1.8 h (parent), ~4.2 h (acid); absolute bioavailability <5%; food has minimal effect | Take in the evening; food does not require dose adjustment |
| Distribution | Plasma protein binding ~95%; lipophilic — distributes broadly into tissues including muscle | Greater extrahepatic exposure than hydrophilic statins; contributes to higher myopathy risk profile at high doses |
| Metabolism | Extensive CYP3A4 (and CYP3A5) metabolism in intestine and liver; active metabolites including 6′-hydroxy, 6′-hydroxymethyl, and 6′-exomethylene simvastatin acid | The dominant source of clinically important drug interactions; grapefruit juice (intestinal CYP3A4 inhibitor) significantly elevates exposure |
| Elimination | ~60% excreted in feces, ~13% in urine (mostly as metabolites); t½ short (~2 h parent, ~2–4 h acid) | Short half-life is the basis for evening dosing; severe renal impairment requires dose reduction |
Side Effects
Adverse-effect frequencies below are from the simvastatin controlled clinical trials database (n = 2,423, median follow-up 18 months) and the major outcome trials (4S, HPS, SEARCH), as reported in the current FDA Zocor prescribing information. Real-world rates of muscle and gastrointestinal symptoms are typically higher than pivotal-trial reports because of selection criteria and the well-described nocebo effect.
No adverse reaction crossed the 10% threshold in the FDA Zocor pre-marketing clinical-trial database. Pooled observational data place statin-associated muscle symptoms in the 5–10% range, but these signals are not represented in the placebo-controlled labelling tables. The most common reactions (≥5%) are listed in the next tier.
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Upper respiratory tract infection | 9% | Likely background population rate rather than drug-attributable |
| Headache | 7% | Generally mild; usually resolves within weeks |
| Abdominal pain | 7% | Usually mild; rule out gallbladder disease if severe or worsening |
| Constipation | 7% | Typically responsive to fiber and hydration |
| Nausea | 5% | Usually transient; take in evening with light snack if bothersome |
| Asymptomatic ALT/AST elevation >3× ULN (persistent) | ~0.9% at 40 mg; ~2.1% at 80 mg | Reversible on discontinuation; not predictive of clinical hepatotoxicity |
| Asymptomatic CK elevation ≥3× ULN | ~5% | Most attributable to non-cardiac CK fraction; not by itself an indication to stop |
| New-onset diabetes mellitus (statin class effect) | ~1–2% excess risk | Concentrated in patients with prediabetes / metabolic syndrome; CV benefit substantially outweighs glycemic risk |
Other adverse reactions reported in clinical trials: diarrhea, rash, dyspepsia, flatulence, asthenia, myalgia (each at lower frequency than the items above).
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Myopathy (CK >10× ULN with symptoms) — clinical trial database (24,747 patients, median 4 years) | ~0.03% (20 mg) · ~0.08% (40 mg) · ~0.61% (80 mg) | Highest in first year; then declines | Discontinue; rechallenge with lower dose or alternate statin only after resolution |
| Myopathy in SEARCH (12,064 post-MI patients, mean 6.7 years) | ~0.02% (20 mg) · ~0.9% (80 mg) | First year | Underlies the FDA 2011 restriction on the 80 mg dose |
| Rhabdomyolysis (CK >40× ULN) — SEARCH | ~0% (20 mg) · ~0.4% (80 mg) | Weeks–months | Stop drug immediately; check CK and renal function; aggressive hydration; avoid all statins until resolved |
| Immune-mediated necrotizing myopathy (IMNM) | Very rare (~2 per million person-years across statin class) | Months–years; persists or worsens after stopping | Permanent discontinuation; check anti-HMGCR antibody; refer to neurology / rheumatology for immunosuppressive therapy |
| Fatal and non-fatal hepatic failure | Rare (post-marketing) | Weeks–months | Discontinue if jaundice or hyperbilirubinemia; evaluate for other causes |
| Hypersensitivity (anaphylaxis, angioedema, Stevens-Johnson syndrome, DRESS) | Rare (post-marketing) | Days–weeks | Permanent discontinuation; avoid all statins after anaphylaxis or severe cutaneous reaction |
| Cognitive impairment (memory loss, confusion — usually reversible) | Rare (post-marketing, statin class label) | Days to years; resolution typically within weeks of stopping | Trial of discontinuation if temporally related; not a contraindication to future statin therapy |
| Interstitial lung disease, peripheral neuropathy, thrombocytopenia, pancreatitis, polymyositis / dermatomyositis (statin class) | Very rare (post-marketing) | Months–years | Discontinue if temporally related and other causes excluded |
| Reason for Discontinuation | Context | Comment |
|---|---|---|
| Gastrointestinal disorders | 0.5% in pre-marketing trials | Most common reason; usually settles or improves with food / evening dosing |
| Myalgia | 0.1% in pre-marketing trials | Real-world rate is meaningfully higher; remains the most common open-label reason for discontinuation |
| Arthralgia | 0.1% in pre-marketing trials | Often resolves after a few weeks |
| Hepatic enzyme elevation | ~0.9% (40 mg) to ~2.1% (80 mg) develop persistent ALT/AST >3× ULN; not all discontinue | Many cases resolve on dose reduction; rarely indicative of clinical hepatotoxicity |
| Hypersensitivity | Permanent discontinuation indicated | Switch class if needed |
Pediatric data (24-week controlled trial in 175 HeFH patients ages 10–17, with 144 in 24-week extension): adverse-reaction profile was similar to placebo; the most common adverse reactions were upper respiratory infection, headache, abdominal pain, and nausea. No detectable effect on growth or sexual maturation; doses >40 mg/day not studied in this population.
For simvastatin specifically, drug-interaction-related myopathy is the dominant risk: a careful medication review (CYP3A4 inhibitors, including grapefruit juice ≥1 quart/day) often identifies a reversible cause. Stepwise approach: (1) confirm symptoms with a 4–6 week drug holiday; (2) check TSH, vitamin D, and creatinine; (3) review for new CYP3A4 inhibitors or interacting drugs; (4) if true SAMS confirmed, consider switching to a hydrophilic statin (rosuvastatin or pravastatin), which is less prone to CYP3A4-driven myotoxicity; (5) if statin truly intolerated, escalate to ezetimibe ± PCSK9 inhibitor or bempedoic acid.
Drug Interactions
Simvastatin’s interaction profile is dominated by CYP3A4 inhibition. Strong CYP3A4 inhibitors are contraindicated; moderate CYP3A4 inhibitors require specific dose caps. Simvastatin acid is also a substrate of OATP1B1, accounting for the contraindications with cyclosporine and gemfibrozil. Always review the full medication list — including prescription, OTC, herbal (St. John’s wort), and dietary (grapefruit juice) — before initiating, escalating, or refilling simvastatin.
Monitoring
-
Lipid Panel
Baseline; reassess as early as 4 weeks; then 4–12 weeks after dose change; then annually
Routine Confirm percent LDL-C reduction (~32% expected at 20 mg, ~37% at 40 mg per VOYAGER). If <50% reduction is needed, switch to a higher-intensity statin rather than escalate simvastatin to 80 mg. Adherence is a more common reason for inadequate response than non-response. -
ALT / AST
Baseline; thereafter only if symptoms
Trigger-based Routine periodic LFTs are no longer recommended. Repeat if patient develops jaundice, fatigue, abdominal pain, dark urine, or unexplained nausea. Discontinue if ALT/AST >3× ULN with symptoms or hyperbilirubinemia. -
Creatine Kinase (CK)
Baseline only in high-risk patients; otherwise only if symptoms
Trigger-based High-risk = age ≥65, hypothyroidism, renal impairment, prior statin myopathy, Chinese ancestry on niacin, or concomitant CYP3A4 inhibitor. Check if patient develops myalgia, weakness, or dark urine. Stop if CK >10× ULN with symptoms. -
Medication Reconciliation
Every visit and at every new prescription
Routine Specifically check for new CYP3A4 inhibitors (especially azole antifungals, clarithromycin, ritonavir-containing antiretrovirals, cobicistat, calcium channel blockers, amiodarone) and grapefruit juice intake. Adjust dose or switch agents proactively. -
HbA1c / Fasting Glucose
Baseline; periodically if at risk for diabetes
Routine Modest excess incidence of new-onset diabetes (mostly in patients with prediabetes). CV benefit greatly outweighs glycemic risk; do not stop the statin if A1c rises into diabetic range. -
Renal Function
Baseline; per overall comorbidity profile
Routine Estimate CrCl/eGFR before initiation and recheck if clinical change. Severe CKD (CrCl <30 mL/min/1.73 m²) requires starting at 5 mg. -
TSH
If unexplained myalgia or rising CK
Trigger-based Unrecognized hypothyroidism is a major contributor to apparent statin intolerance and CK rise; treat the thyroid before declaring statin intolerance. -
Adherence Check
Every clinical visit
Routine Approximately half of patients discontinue statins within 1 year of initiation. Open, non-judgemental questioning (“How often do you forget?”) yields more accurate information than yes/no adherence questions. Confirm patient is taking the dose in the evening. -
Pregnancy Status
In females of reproductive potential, periodically
Trigger-based FDA removed the pregnancy contraindication in July 2021. Statins are generally discontinued during planned or confirmed pregnancy unless benefits clearly outweigh risk (e.g., HoFH or established ASCVD). Effective contraception is recommended during therapy.
Contraindications & Cautions
Absolute Contraindications (per current FDA Zocor PI, Organon 2023)
- Concomitant use of strong CYP3A4 inhibitors — including itraconazole, ketoconazole, posaconazole, voriconazole, erythromycin, clarithromycin, telithromycin, HIV protease inhibitors (e.g., ritonavir, nelfinavir, darunavir/ritonavir), boceprevir, telaprevir, nefazodone, and cobicistat-containing products.
- Concomitant cyclosporine, danazol, or gemfibrozil.
- Hypersensitivity to simvastatin or any formulation excipient (anaphylaxis, angioedema, and Stevens-Johnson syndrome have been reported).
Note on label discrepancy: The FloLipid (oral suspension) prescribing information additionally lists “active liver disease, which may include unexplained persistent elevations in hepatic transaminase levels” as a contraindication. The current Zocor (tablet) PI does not include this in its Contraindications section but addresses hepatic dysfunction under Warnings and Precautions. Clinicians prescribing the suspension formulation should follow the FloLipid label.
Relative Contraindications (Specialist Input Recommended)
- Acute liver failure or decompensated cirrhosis — although not listed in the Zocor PI Contraindications section, statins are generally avoided. The Zocor PI states use with caution in chronic alcohol use or prior liver disease and lists hepatic dysfunction as a Warning.
- Pregnancy — although the FDA removed the contraindication in 2021, statins are still typically discontinued during planned or confirmed pregnancy. Continued use is reasonable only in HoFH or established ASCVD where lipid-lowering benefit clearly outweighs theoretical fetal risk; document the explicit risk-benefit discussion. For most patients, switching to a hydrophilic statin (rosuvastatin, pravastatin) or stopping is preferred.
- Lactation — breastfeeding is not recommended during simvastatin therapy; if therapy is required postpartum, use formula.
- Severe renal impairment (CrCl <30 mL/min/1.73 m²) — start at 5 mg/day with close monitoring.
- History of statin-induced rhabdomyolysis or immune-mediated necrotizing myopathy — IMNM is a permanent contraindication to all statins; uncomplicated SAMS may permit cautious rechallenge with a different statin.
- Currently tolerating 80 mg with new interacting drug — switch to an alternate statin rather than continuing 80 mg with the interacting agent.
Use with Caution
- Chinese ancestry on lipid-modifying niacin — do not exceed 20 mg simvastatin with niacin ≥1 g/day; avoid the 80 mg dose with niacin in this group entirely.
- Age ≥65 years — frailty, polypharmacy, and lower muscle mass raise myopathy risk; start at 10 mg.
- Hypothyroidism — treat first; untreated hypothyroidism amplifies myopathy risk and may itself elevate CK.
- Concomitant fibrates (especially fenofibrate), niacin (≥1 g/day), colchicine, or daptomycin — additive myotoxicity; counsel on muscle symptoms and consider temporarily suspending simvastatin during a daptomycin course.
- Diabetes risk factors (prediabetes, metabolic syndrome) — small excess diabetes incidence; CV benefit nonetheless outweighs risk.
- Major surgery, sepsis, severe trauma, or other acute serious medical conditions — temporarily withhold simvastatin in any patient at high risk of rhabdomyolysis.
- Pediatric patients <10 years — efficacy and safety not established below age 10.
- Myasthenia gravis or ocular myasthenia — case reports of new onset or worsening with statin use; weigh carefully.
The FDA restricted use of the simvastatin 80 mg dose because of an increased risk of muscle injury, particularly during the first year of therapy. Simvastatin 80 mg should not be initiated in new patients. The 80 mg dose is reserved only for patients who have been taking it chronically (≥12 months) without evidence of muscle toxicity. For patients on 40 mg who are not at LDL-C goal, prescribe an alternative LDL-C-lowering treatment (different statin or addition of ezetimibe or PCSK9 inhibitor) rather than escalating to 80 mg. Patients tolerating 80 mg who are starting an interacting drug must be switched to an alternate statin.
Risk basis: in the SEARCH trial (12,064 post-MI patients, 6.7 years), myopathy occurred in approximately 0.9% on 80 mg vs 0.02% on 20 mg, with rhabdomyolysis in 0.4% vs 0%.
The FDA requested removal of the contraindication against statin use in pregnancy from the labeling of all statins. The change does not endorse routine use; it allows individualized risk-benefit decisions, particularly for women with HoFH, established ASCVD, or very high CV risk.
Most patients should still discontinue statins on confirmation of pregnancy. Lactation remains a reason to defer therapy because of potential infant exposure; patients who require ongoing statin therapy postpartum should not breastfeed.
All HMG-CoA reductase inhibitors carry a class-wide warning regarding myopathy and rhabdomyolysis. Simvastatin’s CYP3A4-driven metabolism makes it particularly susceptible to dose-dependent and interaction-driven myopathy. Risk factors include age ≥65 years, uncontrolled hypothyroidism, renal impairment, female sex, low body weight, Chinese ancestry, and concomitant interacting drugs.
Counsel every patient to promptly report unexplained muscle pain, tenderness, weakness, or dark urine. Discontinue immediately if rhabdomyolysis is suspected or if CK rises >10× ULN with symptoms. Temporarily withhold simvastatin in any patient with an acute serious condition predisposing to rhabdomyolysis (sepsis, hypotension, dehydration, major surgery, severe metabolic or electrolyte disorder, uncontrolled seizures).
Patient Counselling
Purpose of Therapy
Simvastatin lowers LDL (“bad”) cholesterol by reducing the liver’s production of cholesterol. Lower LDL means less plaque buildup inside arteries, which reduces the chance of heart attacks, strokes, and the need for procedures such as stents or bypass surgery. The benefit accumulates over years — most patients are taking it for prevention rather than for symptom relief, so they may not “feel” anything different. Lifestyle measures (diet, exercise, weight control, smoking cessation) act on the same arteries and add to the benefit.
How to Take
Take one tablet once a day, in the evening, with or without food. Evening dosing matters for this medicine specifically — the body makes most of its cholesterol overnight, so an evening dose works better than a morning dose. If a dose is missed, take it as soon as remembered the same evening; if the next dose is due within a few hours, skip the missed one and continue normally. Do not double up. Avoid drinking large amounts of grapefruit juice (more than about a quart per day); occasional small servings are fine. Do not stop the medicine without speaking to the prescriber, even if cholesterol numbers look good — stopping is when the protection fades.
Sources
- ZOCOR (simvastatin) US Prescribing Information. Organon LLC; revised 2023. Accessed via FDA Drugs@FDA. accessdata.fda.gov/drugsatfda_docs/label/2023/019766Orig1s103lbl.pdf Authoritative source for FDA-approved indications, dosing limits, contraindications, drug interactions, and adverse-reaction frequencies cited in this monograph.
- FLOLIPID (simvastatin) Oral Suspension US Prescribing Information. Salerno Pharmaceuticals. Available via DailyMed. dailymed.nlm.nih.gov Reference for the oral suspension formulation; note that this label retains “active liver disease” as a contraindication, which differs from the current Zocor tablet PI.
- FDA Drug Safety Communication: New restrictions, contraindications, and dose limitations for Zocor (simvastatin) to reduce the risk of muscle injury. June 8, 2011. fda.gov Underlies the 80 mg restriction and the dose caps with amiodarone, calcium channel blockers, and other interacting drugs.
- FDA Drug Safety Communication: FDA requests removal of strongest warning against using cholesterol-lowering statins during pregnancy. July 20, 2021. fda.gov The 2021 labeling change removing the pregnancy contraindication for the entire statin class.
- Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet. 1994;344(8934):1383-1389. doi:10.1016/s0140-6736(94)90566-5 First statin outcome trial showing a mortality benefit; underpins the secondary-prevention indication.
- Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet. 2002;360(9326):7-22. doi:10.1016/S0140-6736(02)09327-3 Demonstrated CV benefit across diabetes, peripheral vascular disease, and prior stroke regardless of baseline LDL-C; basis for broad high-risk indication.
- SEARCH Collaborative Group. Intensive lowering of LDL cholesterol with 80 mg versus 20 mg simvastatin daily in 12,064 survivors of myocardial infarction: a double-blind randomised trial. Lancet. 2010;376(9753):1658-1669. doi:10.1016/S0140-6736(10)60310-8 Source for the myopathy and rhabdomyolysis rates that triggered the FDA 2011 restriction on the 80 mg dose.
- HPS2-THRIVE Collaborative Group. Effects of extended-release niacin with laropiprant in high-risk patients (HPS2-THRIVE). N Engl J Med. 2014;371(3):203-212. doi:10.1056/NEJMoa1300955 Identified excess myopathy in Chinese patients on simvastatin plus niacin and the absence of CV benefit from niacin add-on therapy.
- Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. Circulation. 2019;139(25):e1082-e1143. doi:10.1161/CIR.0000000000000625 Primary US guideline; classifies simvastatin 20–40 mg as moderate intensity and 10 mg as low intensity.
- Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J. 2020;41(1):111-188. doi:10.1093/eurheartj/ehz455 European framework with lower LDL-C targets in very-high-risk patients; supports preferential use of high-intensity statins over simvastatin in these populations.
- Newman CB, Preiss D, Tobert JA, et al. Statin Safety and Associated Adverse Events: A Scientific Statement From the American Heart Association. Arterioscler Thromb Vasc Biol. 2019;39(2):e38-e81. doi:10.1161/ATV.0000000000000073 Comprehensive class-wide safety review used here for myopathy framing, observational vs RCT muscle-symptom rates, and diabetes risk discussion.
- Cholesterol Treatment Trialists’ (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet. 2010;376(9753):1670-1681. doi:10.1016/S0140-6736(10)61350-5 Class-wide meta-analysis underpinning the “lower is better” LDL-C principle and magnitude-of-benefit framing in this monograph.
- Karlson BW, Palmer MK, Nicholls SJ, Lundman P, Barter PJ. Variability of low-density lipoprotein cholesterol response with different doses of atorvastatin, rosuvastatin, and simvastatin: results from VOYAGER. Eur Heart J Cardiovasc Pharmacother. 2016;2(4):212-217. doi:10.1093/ehjcvp/pvw006 Source for the simvastatin LDL-C reduction data (28% at 10 mg to 46% at 80 mg) used throughout the monograph.
- SEARCH Collaborative Group. SLCO1B1 variants and statin-induced myopathy — a genomewide study. N Engl J Med. 2008;359(8):789-799. doi:10.1056/NEJMoa0801936 Established the SLCO1B1 (OATP1B1) variant rs4149056 as the major genetic determinant of simvastatin-induced myopathy risk.