Simvastatin: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on May 16, 2024.

1. How it works

• Simvastatin works by blocking an enzyme in the liver known as HMG-CoA reductase that is responsible for the conversion of HMG-CoA to mevalonate, an important substance necessary for the synthesis of cholesterol and coenzyme Q10.
• Simvastatin also boosts the breakdown of lipids.
• Simvastatin belongs to a group of drugs known as HMG-CoA reductase inhibitors or statins.

2. Upsides

• Simvastatin, in conjunction with dietary measures, is used in people at high risk of having a heart event to:

• Reduce the risk of death from cardiovascular disease
• Reduce the incidence of non-fatal heart attack and stroke
• Reduce the need for revascularization procedures.

• People considered at increased risk of a heart event include those with diabetes, a history of stroke or a similar event, with pre-existing heart disease, or with peripheral vascular disease.
• Simvastatin is also used to reduce high levels of lipids in people with elevated cholesterol levels. Simvastatin reduces total cholesterol, LDL-cholesterol, apolipoprotein B, and triglycerides, and increases high-density lipoproteins.
• Simvastatin is also indicated in some genetic lipid disorders (such as heterozygous familial hypercholesterolemia) in adolescents aged 10 to 17 meeting certain criteria.
• The dosage of simvastatin does not need adjusting in mild-to-moderate kidney disease. Patients with severe kidney disease should be started on simvastatin 5mg daily and monitored.
• Generic simvastatin is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• A headache, abdominal pain, nausea, and constipation.
• Myopathy (muscle pain), tenderness, or weakness - initially needs further investigation to determine severity.
• Rarely, severe muscle pain and rhabdomyolysis (a breakdown in muscle tissue) have been reported. The risk is greater in people taking more than 80mg of simvastatin per day, older than 65, females, with uncontrolled hypothyroidism, or kidney disease.
• People of Chinese descent are more likely to develop myopathy. The risk is greater at dosages greater than 20 mg/day or when simvastatin is combined with niacin-containing products.
• Should not be used by people with active liver disease or in women planning a pregnancy.
• May interact with several other medications (see below).
• May increase liver enzymes (increases of up to three times the upper normal limit have been reported).
• Do not use it during pregnancy, and women who are taking simvastatin should not breastfeed. If taken during pregnancy, simvastatin may interfere with the synthesis of steroids and cell membranes in the fetus.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Simvastatin is effective at lowering cholesterol; however, it may cause muscle pain, particularly at higher dosages. Should not be used by people with active liver disease or in women planning a pregnancy or who are pregnant.

5. Tips

• Take once daily in the evening and avoid large quantities of grapefruit juice.
• Adhere to the National Cholesterol Education Program recommendations while taking simvastatin. These include following the therapeutic lifestyle changes, which include a daily dietary intake of less than 7% of calories from saturated fat, less than 200 mg of dietary cholesterol, and 25% to 35% of daily calories from total fat, provided most is from unsaturated fat. Foods containing plant stanols and sterols (such as certain margarines and salad dressings) should be eaten as well as soluble fiber (including cereal grains, beans, peas, legumes, fruits, and vegetables). Weight should be controlled and physical activity increased.
• Regular exercise is also important as well as avoiding smoking.
• The dosage needs to be individualized but higher dosages (ie, 80 mg/day) should not be used unless they are shown to be tolerated without causing muscle pain. If higher dosages are needed, your doctor may consider an alternative statin (ie, atorvastatin, rosuvastatin).
• Regular blood tests are needed (after 4 weeks of therapy then periodically thereafter) to determine the effect of simvastatin on lipids and other factors (such as liver function).
• Report to your doctor immediately if you experience any unexplained muscle pain, tenderness, or weakness, particularly if associated with tiredness or fever.
• Simvastatin should not be taken during pregnancy or while breastfeeding. Ensure you use effective contraception while taking simvastatin if you are a woman of childbearing age and talk to your doctor if you intend to become pregnant before you actually become pregnant.

6. Response and effectiveness

• Simvastatin is a prodrug, which means it is converted into its active beta-hydroxyacid form, after administration.
• Peak levels are seen within 1.3 to 2.4 hours following administration; however, it may take up to one to two weeks of regular dosing before improvements in lipid levels are seen.
• Simvastatin reduces cholesterol, Very Low-Density Lipoproteins (VLDL), and triglycerides while increasing HDL cholesterol.

7. Interactions

Medicines that interact with simvastatin may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with simvastatin. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with simvastatin include:

• amiodarone
• antibiotics, such as erythromycin
• antidepressants, such as nefazodone
• antifungals, such as itraconazole, ketoconazole, posaconazole, or voriconazole
• calcium channel blockers such as amlodipine, diltiazem, or verapamil
• colchicine
• digoxin
• niacin
• other lipid-lowering drugs such as gemfibrozil and bezafibrate
• other strong CYP3A4 inhibitors, such as clarithromycin, cyclosporine, or ritonavir
• warfarin.

Note that this list is not all-inclusive and includes only common medications that may interact with simvastatin. You should refer to the prescribing information for simvastatin for a complete list of interactions.

References

• Simvastatin. Revised 08/2024. Northstar Rx LLC https://www.drugs.com/pro/simvastatin.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use simvastatin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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