Simvastatin: what it is used for, dosage and side effects

What simvastatin is and which active substance it contains

Simvastatin belongs to the group of HMG-CoA reductase inhibitors, universally called statins. In the Maltese register of medicines the entry simvastatin is recorded with simvastatin as its active substance and the oral route of administration, and the same substance appears on that register under several other names from other companies, as well as in fixed combination with fenofibrate.

When the substance and the product share a name it is easy to assume that any pack labelled with it is interchangeable with any other. The strength is what differs, and with this substance the strength is precisely what the interactions turn on, so a pack is not simply a pack. If your tablets change in appearance after a repeat, check the strength printed on them against your prescription and ask a pharmacist if the two do not obviously match.

A combination tablet containing simvastatin with another lipid-lowering substance already contains the statin. Adding plain simvastatin to it would mean taking the same substance twice, which is a real and easily made mistake rather than a theoretical one.

Read the leaflet supplied with your own pack before you start it, because wording on warnings and interactions is revised from time to time and this substance has had its guidance tightened over the years. Authorised products in Malta and their product information are listed by the Medicines Authority. What raised cholesterol means is described at /health-guide/high-cholesterol/ and the wider picture at /heart-and-cholesterol/.

What it is used for

Simvastatin is used to lower raised cholesterol, in particular the fraction carried by low-density lipoprotein, and to reduce cardiovascular risk in people in whom that risk is judged to be high. As with every statin, the target of the treatment is the risk of heart attack and stroke rather than the appearance of the laboratory report.

The doctor sets that risk from the lipid profile together with blood pressure, smoking, diabetes, kidney function, family history, age and any cardiovascular event you have already had. Which statin is chosen, and at what strength, follows from that assessment and from what else you take, and it is one of the places where the differences between statins genuinely matter.

The medicine does not replace diet, physical activity, stopping smoking and body weight, all of which change the size of the risk it is working against. Nor does it produce any sensation: raised cholesterol has no symptoms, so the treatment is judged on blood tests and not on how well you feel.

How simvastatin works and why it is taken in the evening

Most of the cholesterol in your blood is manufactured by the liver rather than eaten, and the decisive step in that manufacture is performed by the enzyme HMG-CoA reductase. Simvastatin blocks it, so the liver produces less. The liver then increases the number of receptors that pull LDL particles out of the bloodstream, so the level falls both because less is made and because more is removed.

The liver does most of that manufacturing at night, while you are not eating. Simvastatin is a relatively short-acting statin, so its effect is greatest during the hours after a dose; taking it in the evening lines the medicine up with the period of greatest production, which is why the leaflet for this substance says evening while the leaflet for a longer-acting statin may not care. Follow the instruction for your own pack rather than a general rule.

Statins also make existing deposits in the artery wall more stable and so less likely to rupture, which is the event behind most heart attacks. That benefit does not appear in the lipid profile at all, and it is part of why the treatment is worth more than the change in the numbers suggests.

The effect lasts only while the medicine is taken. After stopping, the liver returns to its earlier rate of production and the level drifts back, with nothing you can feel to tell you it has happened.

How it is taken and what to watch for

The strength and the dose are set by the doctor from your lipid profile and your calculated risk, and adjusted against a repeat test. The tablet is swallowed whole with water, usually in the evening, and the schedule for your pack is in its leaflet. If you also take another medicine that limits how much simvastatin may be given, the doctor takes that into account when choosing the strength, and it is not something to adjust yourself.

The medicine is not used in pregnancy or while breastfeeding, and women who could become pregnant are advised to use reliable contraception while taking it. It is also not used where there is hypersensitivity to the substance, in active liver disease and where liver enzymes are persistently and unexplainedly raised, or together with the medicines listed in your product information as absolutely not to be combined with it. These are contraindications rather than matters of extra care; if you are pregnant or planning a pregnancy, tell the doctor, because the treatment is stopped.

Particular care and a decision by the doctor are needed where there is a history of liver disease, in significant alcohol intake, in reduced kidney function, in an underactive thyroid, in inherited muscle disorders or where a previous statin caused muscle problems, and in older patients. Liver enzymes are usually checked before treatment and afterwards as the doctor judges necessary.

Muscle symptoms come with their own instruction, and with this statin they deserve particular attention because the risk rises with the strength used and with certain combinations. Aching, tenderness, weakness or cramp in the muscles, especially if widespread or accompanied by dark urine, fever or feeling generally unwell, should be reported rather than dealt with by stopping the tablet quietly. Severe, unexplained muscle pain with dark urine needs urgent assessment.

Interactions with other medicines

This is the section that matters most for this particular statin. Simvastatin is broken down by the liver enzyme system CYP3A4, and it is more sensitive to interference with that system than most of its group. The result is a genuine division: with some medicines the combination is not permitted at all, and with others the doctor caps the strength of simvastatin rather than forbidding it.

Among the medicines that raise simvastatin levels are itraconazole, ketoconazole and other antifungals, macrolide antibiotics such as clarithromycin and erythromycin, telithromycin, medicines containing ritonavir and other protease inhibitors, nefazodone, ciclosporin, danazol and gemfibrozil. Several calcium channel blockers, including amlodipine, diltiazem and verapamil, and the antiarrhythmic amiodarone also require the strength to be limited, which is why a patient on treatment for blood pressure or heart rhythm may be given a lower strength than someone of the same cholesterol level who is not.

Grapefruit and grapefruit juice affect the same enzyme system through what you eat and drink, so large or regular amounts are not recommended with this medicine. Other lipid-lowering medicines, in particular the fibrates, and high doses of nicotinic acid add to the risk of muscle problems. Care is also needed with colchicine, with digoxin and with anticoagulants of the coumarin type, where clotting tests may need checking more often around a dose change.

Because the list is long and the consequence of ignoring it is muscle damage, the single most useful habit is to mention that you take simvastatin every time any new medicine is prescribed by anybody, and to have a pharmacist review your full list, including products bought without a prescription, food supplements and herbal preparations. A short antibiotic course started by someone who does not know about the statin is the classic way this goes wrong.

Side effects and when to seek help

Statins are generally well tolerated, and simvastatin is no exception at the strengths at which it is usually given. The effects described most often include headache, digestive complaints such as nausea, constipation, wind and abdominal pain, muscle and joint pain, and a rise in liver enzymes on blood tests.

Less often, dizziness, tingling or numbness in the hands and feet, difficulty sleeping, nightmares, blurred vision, rash and itching are reported, as are memory problems, which are described with this group and which reverse when the medicine is stopped.

Rare but serious events include inflammation of the muscles and rhabdomyolysis, a severe breakdown of muscle tissue that can damage the kidneys and whose likelihood rises with higher strengths and with the combinations listed above; inflammation of the liver with jaundice; inflammation of the pancreas; severe skin and hypersensitivity reactions; and an immune-mediated muscle disease that can persist after stopping.

Seek medical help without delay for unexplained muscle pain, tenderness or weakness, particularly with dark urine, fever or feeling generally unwell; for yellowing of the skin or the whites of the eyes; for severe abdominal pain; for a widespread blistering rash; and for swelling of the face or tongue with difficulty breathing. In a life-threatening situation call 112 or go to Accident and Emergency. The complete list of side effects with information on how often each occurs is in the leaflet supplied with your pack, and a suspected side effect can be reported to your doctor or pharmacist; safety of medicines on the Maltese market is monitored by the Medicines Authority.

Prescription status and what we can do

Simvastatin is a prescription-only medicine in Malta, so the decision to start it and the strength belong to a doctor, and with this substance the strength depends on what else you take. We do not sell medicines and we cannot send you one. What we offer is a written medical questionnaire and a doctor review of your answers. There is no video call, no telephone consultation and no live chat.

We are not part of any Maltese state health record and we write nothing into one. The doctor issues a cross-border prescription in the format set out in the Annex to Directive 2012/52/EU, which reaches you as a PDF by e-mail. You print it or show it on screen at the pharmacy, together with a photo identity document. There is no code and no number to quote, and a pharmacy in Malta may dispense it; the decision rests with the pharmacist, who can refuse if the document is illegible or if its authenticity is in doubt.

If simvastatin has already been started for you and this is a continuation of established treatment, you can fill in the questionnaire at /repeat-prescription/. The review is carried out by lek. Damian Wojno, a doctor registered with the Polish Medical Chamber, licence no. 3211301; he is not registered with the Medical Council of Malta. Give your full list of medicines in the questionnaire, because with this statin the list determines the strength. A recent lipid profile and recent liver enzymes are the results the doctor asks for most often. We do not start this treatment for the first time from a questionnaire, and we do not deal this way with unexplained muscle pain or the other warning signs described above.

The assessment costs 24,90 €, with an optional priority surcharge of 9,90 €. The fee covers the medical consultation, not the issuing of a document, and it is not funded by the Maltese public health system. If the doctor declines on medical or legal grounds, we refund the fee. If the doctor asks for documents, you have at least seven days to send them in, and if the consultation cannot be completed, we close the request and refund the fee in full. The medicine itself is paid for separately at the pharmacy; what the fee does and does not cover is set out at /blog/online-prescription-cost-malta/.