Simvastatin Tablets

Simvastatin has been one of the most widely prescribed statins in the UK for several decades, with a well-established evidence base for cholesterol lowering and cardiovascular risk reduction. Simvastatin tablets are a prescription-only statin used in adults for primary hypercholesterolaemia, mixed dyslipidaemia, and secondary prevention of cardiovascular events. Simvastatin is an important medicine in lipid management, though prescribers and patients should be aware of its significant drug interaction profile, it interacts with a wider range of medicines than most other statins due to its CYP3A4 metabolism. A prescription can only be issued following a clinical consultation.

IMPORTANT — SIMVASTATIN 80mg: The MHRA has restricted Simvastatin 80 mg due to an increased risk of myopathy and rhabdomyolysis at this dose. Simvastatin 80 mg must not be initiated in new patients and must not be used to increase the dose of patients who are not already established on Simvastatin 80 mg. It should only be prescribed to patients who have been taking Simvastatin 80 mg for 12 months or more without muscle toxicity. If a patient requires more intensive lipid lowering, switching to an alternative higher intensity statin such as atorvastatin is preferred over initiating Simvastatin 80 mg.

Simvastatin tablets are an oral prescription medicine containing Simvastatin as the active ingredient. Simvastatin belongs to the statin class of lipid-lowering medicines (HMG-CoA reductase inhibitors). It is one of the older statins in clinical use and remains widely prescribed as a generic medicine at low cost. Simvastatin is a prodrug that is converted in the liver to Simvastatin acid, its active form.

Simvastatin is licensed in the UK for: primary hypercholesterolaemia; mixed hyperlipidaemia; homozygous familial hypercholesterolaemia alongside dietary measures; secondary prevention of cardiovascular events (heart attack and stroke) in patients with cardiovascular disease or at high cardiovascular risk. The 4S trial, one of the landmark statin trials, used Simvastatin and provided foundational evidence for statin therapy in secondary prevention.

Simvastatin is available in four strengths: 10 mg, 20 mg, 40 mg, and 80 mg. At 40 mg and above, Simvastatin is considered a medium to high intensity statin. The 80 mg strength carries a specific MHRA restriction. NICE guideline NG238 generally recommends atorvastatin as the preferred high intensity statin for most adults requiring cardiovascular risk reduction.

Simvastatin lowers cholesterol through HMG-CoA reductase inhibition, the same mechanism as all statins.

Prodrug Activation and HMG-CoA Reductase Inhibition. Simvastatin is a prodrug. After absorption, it is hydrolysed in the liver to Simvastatin acid, the active form. Simvastatin acid competitively inhibits HMG-CoA reductase, the enzyme catalysing the rate-limiting step in hepatic cholesterol synthesis. Reduced intracellular cholesterol triggers upregulation of LDL receptors on liver cell surfaces. These additional receptors capture more LDL cholesterol from the bloodstream, lowering circulating LDL levels. Simvastatin also modestly lowers triglycerides and raises HDL cholesterol.

CYP3A4 Metabolism and Interaction Profile. Simvastatin is extensively metabolised by the CYP3A4 enzyme. This gives it a wider and more clinically significant drug interaction profile than statins such as pravastatin (minimal CYP metabolism) and rosuvastatin (primarily CYP2C9). Medicines that inhibit CYP3A4, including grapefruit juice, itraconazole, ketoconazole, erythromycin, clarithromycin, HIV protease inhibitors, and ciclosporin, can raise Simvastatin acid levels substantially, greatly increasing myopathy and rhabdomyolysis risk. Several of these combinations are contraindicated. Medicines that require a Simvastatin dose limit (such as amiodarone, verapamil, diltiazem, and amlodipine) are also more numerous for Simvastatin than for most other statins.

Patients starting Simvastatin should inform their prescriber about all medicines they take, including antibiotics, antifungals, and medicines for HIV or heart conditions, before Simvastatin is prescribed or dispensed.

Always take Simvastatin exactly as your prescriber instructs. Read the Patient Information Leaflet supplied with your medicine before starting treatment.

• Take Simvastatin once daily in the evening, as cholesterol synthesis is highest overnight.
• Simvastatin can be taken with or without food.
• Avoid grapefruit and grapefruit juice throughout treatment, as even moderate amounts can raise Simvastatin blood levels substantially.
• Swallow the tablet whole with a glass of water.

If you miss a dose, take it as soon as you remember on the same evening. If you only remember the following day, skip the missed dose and take your next dose the following evening. Do not take two doses on the same day. Do not stop taking Simvastatin without speaking to your prescriber first.

Your prescriber will arrange lipid level monitoring before starting and typically four to twelve weeks after. Liver function may also be checked.

Simvastatin is available in four strengths. The appropriate dose is determined by your prescriber based on your lipid levels, cardiovascular risk, and current medicines.

Simvastatin 10 mg Tablets: The lowest available strength, used as a starting dose in older patients, those with kidney impairment, patients at higher risk of muscle problems, or patients starting statin therapy cautiously.

Simvastatin 20 mg Tablets: A standard starting dose for many adults. After four to twelve weeks, the prescriber will review the lipid response and decide whether to continue or increase the dose. Considered a lower intensity statin dose.

Simvastatin 40 mg Tablets: The most commonly prescribed strength, considered the standard effective dose for most adults with primary hypercholesterolaemia and secondary prevention. Approximately equivalent in intensity to atorvastatin 10 mg.

Simvastatin 80 mg Tablets: Subject to the MHRA restriction described above. Must not be started in new patients. Only appropriate for patients who have been taking it for 12 months or more without evidence of muscle toxicity. For patients requiring more intensive LDL reduction, switching to atorvastatin is the recommended approach rather than initiating or increasing to 80 mg.

Like all statins, Simvastatin can cause side effects.

Common Side Effects (may affect up to 1 in 10 people):

• Muscle aches, pains, or weakness (myalgia). Contact your prescriber promptly if you experience unexplained muscle pain. Do not wait for a scheduled appointment.
• Gastrointestinal effects including abdominal pain, nausea, constipation, and diarrhoea.
• Headache.
• Raised liver enzymes on blood tests.

Uncommon Side Effects (may affect up to 1 in 100 people):

• Sleep disturbances or insomnia.
• Dizziness.
• Skin rash.
• A small increase in the risk of type 2 diabetes, associated with the statin class.

Serious Side Effects — Seek Urgent Medical Attention: Go to your nearest accident and emergency department or call 999 immediately if you experience severe muscle pain, weakness, or cramps, particularly with dark, tea coloured urine (rhabdomyolysis — risk significantly higher with Simvastatin 80 mg and when combined with CYP3A4 inhibitors); signs of significant liver problems such as yellowing of the skin or eyes, severe abdominal pain, or very dark urine; or signs of a severe allergic reaction such as sudden swelling of the face, lips, tongue, or throat.

Simvastatin tablets may be suitable if you:

• Are an adult with primary hypercholesterolaemia, mixed hyperlipidaemia, or homozygous familial hypercholesterolaemia.
• Have cardiovascular disease and require secondary prevention.
• Are not taking any medicines that are contraindicated with Simvastatin.
• Are already prescribed Simvastatin and require a repeat prescription through an online prescribing service.

Simvastatin is not suitable or requires dose adjustment if you:

• Are a new patient requiring Simvastatin 80 mg. This strength is restricted to patients already established on it for 12 months or more without muscle toxicity.
• Are taking a medicine contraindicated with simvastatin, including ciclosporin, danazol, gemfibrozil, strong CYP3A4 inhibitors (itraconazole, ketoconazole, posaconazole, voriconazole, HIV protease inhibitors including cobicistat-containing products, boceprevir, telaprevir, erythromycin, clarithromycin, telithromycin), and nefazodone.
• Are taking amiodarone, verapamil, diltiazem, or amlodipine — these require the Simvastatin dose to be limited.
• Are pregnant or planning to become pregnant. Simvastatin is contraindicated in pregnancy.
• Are breastfeeding.
• Have active liver disease or persistently elevated liver enzymes of unknown cause.
• Have a known allergy or hypersensitivity to Simvastatin or any excipient listed in the SmPC.

Important Drug Interactions — CYP3A4: Grapefruit juice should be avoided throughout treatment due to CYP3A4 inhibition. Contraindicated medicines (must not be taken with Simvastatin at any dose) include ciclosporin, danazol, gemfibrozil, itraconazole, ketoconazole, posaconazole, voriconazole, erythromycin, clarithromycin, telithromycin, nefazodone, HIV protease inhibitors (including lopinavir and ritonavir), cobicistat, boceprevir, and telaprevir. Medicines requiring a Simvastatin dose limit include amiodarone and dronedarone (max 20 mg/day), verapamil and diltiazem (max 20 mg/day), amlodipine and ranolazine (max 20 mg/day), and lomitapide (max 40 mg/day). Warfarin's effect is modestly enhanced — INR monitoring required. Fibrates other than gemfibrozil increase myopathy risk. Colchicine increases myopathy risk.

Simvastatin is a Prescription Only Medicine. The clinical consultation is the essential first step. A prescription will only be issued if a registered prescriber concludes, based on their individual assessment of your circumstances, that Simvastatin is clinically appropriate for you.

During your online consultation with Pharmacy Planet, a registered prescriber will review your cholesterol and lipid levels, cardiovascular risk, current medicines, and relevant medical history. Given simvastatin's extensive interaction profile, the prescriber will pay particular attention to your complete medicines list before making any prescribing decision.

Not all consultations will result in a prescription. The prescriber may recommend atorvastatin or another statin with a lower interaction risk, request blood test results, or advise that a full cardiovascular risk assessment by your GP is needed.