BMA Concise Guide to Medicine & Drugs

Simvastatin

Brand names Simvador, Zocor

Used in the following combined preparation Inegy

QUICK REFERENCE

Drug group Lipid-lowering drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes (except low-dose preparations)

Available as generic Yes

GENERAL INFORMATION

A “statin” type of lipid-lowering drug, simvastatin blocks the action of an enzyme involved in the manufacture of cholesterol in the liver, resulting in lowered blood levels of cholesterol. The drug is prescribed for people with hypercholesterolaemia (high blood cholesterol) who have not responded to other forms of therapy (e.g. a special diet) and who are at risk of developing or have existing coronary heart disease or stroke. Low-dose simvastatin is available over-the-counter. Side effects are usually mild and wear off with time. In the body, simvastatin is found mainly in the liver, and it may raise the levels of liver enzymes but this does not usually indicate serious liver damage. Rarely, it may cause muscle damage, and any unexpected muscle tenderness, pain, or weakness should be reported to your doctor.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily at night.

Adult dosage range 10–80mg daily.

Onset of effect Within 2 weeks; full beneficial effects may not be reached for 4–6 weeks.

Duration of action Up to 24 hours.

Diet advice A low-fat diet is usually recommended. Avoid grapefruit juice.

Storage Keep in original container at room temperature out of the reach of children. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 8 hours, do not take the missed dose, but take the next dose on schedule.

Stopping the drug Do not stop taking the drug without consulting your doctor. Stopping the drug may lead to worsening of the underlying condition.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause liver problems. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Adverse effects of simvastatin are usually mild and do not last long. The most common are gastrointestinal problems (such as abdominal pain, constipation or diarrhoea, nausea, and flatulence), sleep disturbance, and headache. Discuss with your doctor if these are severe. Rarely, simvastatin may cause a rash, jaundice, or muscle pain, tenderness, or weakness. If any of these occur, stop taking the drug and consult your doctor immediately.

INTERACTIONS

Ciclosporin, danazol, fibrates, nicotinic acid, amiodarone, verapamil, diltiazem ranolazine, itraconazole, ketoconazole, HIV protease inhibitors, macrolide antibiotics, and nefazodone Used with simvastatin, these drugs increase the risk of muscle toxicity. If they are required, simvastatin is withheld temporarily or the dose reduced.

St John’s wort reduces blood levels of simvastatin.

Anticoagulants (e.g. warfarin) Simvastatin may increase the effect of these drugs. The level of anticoagulation (INR) should be monitored.

Carbamazepine reduces blood levels of simvastatin. The dose of simvastatin may need to be increased.

Grapefruit juice increases blood levels of simvastatin; regular consumption should be avoided.

SPECIAL PRECAUTIONS

Be sure to consult your doctor or pharmacist before taking this drug if:

· You have liver or kidney problems.

· You have a personal or family history of muscle problems.

· You have porphyria.

· You are taking other medicines.

Pregnancy Not recommended. May affect fetal development. Discuss with your doctor if you are pregnant or intend to become pregnant.

Breast-feeding The drug passes into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Not recommended under 5 years. Reduced dose necessary in older children, under specialist advice.

Over 60 No special problems.

Driving and hazardous work No special problems.

Alcohol Avoid excessive amounts. Alcohol may increase the risk of developing liver problems with this drug.

PROLONGED USE

Prolonged treatment can adversely affect liver function.

Monitoring Periodic blood tests to test for muscle toxicity and assess liver function are recommended.