simvastatin: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
simvastatin: clinical details
Prescribing considerations
- Review medicines, supplements and grapefruit consumption for CYP3A4-, OATP1B1- and muscle-related interactions.
- Assess myopathy risk factors, including renal impairment, uncontrolled hypothyroidism, older age, muscle disorders, previous statin or fibrate toxicity and substantial alcohol use.
- Use cautiously in severe renal impairment and with significant alcohol intake.
- Consider the small class-related increase in blood glucose in patients at high diabetes risk.
- Advise patients to report unexplained muscle pain, tenderness, weakness or cramps promptly.
Contraindications and cautions
- Hypersensitivity to simvastatin or a formulation excipient
- Active liver disease or unexplained persistent serum-transaminase elevation
- Pregnancy and breastfeeding under the selected product licences
- Concurrent potent CYP3A4 inhibitors
- Concurrent gemfibrozil, ciclosporin or danazol
Monitoring
- Check liver function before treatment and subsequently when clinically indicated.
- Measure baseline CK when clinically justified by risk factors.
- Check CK promptly if clinically significant muscle symptoms develop.
- Investigate progressive transaminase elevation, jaundice or other features of significant liver injury.
- Monitor glycaemia in patients at increased diabetes risk.
- Monitor INR appropriately with coumarin anticoagulants.
Clinical pharmacology
Simvastatin is an inactive lactone prodrug hydrolysed mainly in the liver to an active HMG-CoA reductase inhibitor. It undergoes extensive hepatic first-pass extraction, is highly protein bound, is metabolised through CYP3A4 and is transported by OATP1B1 and BCRP.
Formulation and product differences
- The selected tablet is film-coated and contains lactose.
- The selected oral suspensions differ in concentration and flavour: the lower-concentration product is strawberry flavoured and the higher-concentration product is lime flavoured.
- Both selected suspensions contain parabens and propylene glycol and are supplied with a measuring device.
- The suspensions may be given through specified silicone, PVC or polyurethane NG or PEG tubes; use with latex tubes is not supported.
simvastatin preparations and strengths
Oral suspension
Route: Oral
Strengths: 20 mg/5 mL, 40 mg/5 mL
Tablet
Route: Oral
Strengths: 10 mg, 20 mg, 40 mg, 80 mg
simvastatin interactions
Simvastatin has important interactions with medicines that increase its concentration or independently affect muscle.
Potent CYP3A4 inhibitors, including clarithromycin, erythromycin, azole antifungals, HIV protease inhibitors, cobicistat-containing medicines and nefazodone
These can markedly increase simvastatin exposure and muscle-toxicity risk; concurrent use is contraindicated by the selected product information.
Ciclosporin, danazol or gemfibrozil
Concurrent use is contraindicated because of increased simvastatin exposure and risk of myopathy or rhabdomyolysis.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.