Statins are a class of medicines that are frequently used to lower blood cholesterol levels. They do this by blocking the action of a specific chemical in the liver that is necessary for making cholesterol.
Although cholesterol is necessary for normal cell and body function, very high levels of it can lead to atherosclerosis, a condition where cholesterol-containing plaques build up in arteries and block blood flow.
In this article, we will look at how statins work, who uses them, and the associated risks and benefits.
Fast facts on statins
Here are some key points about statins. More detail and supporting information is in the main article.
What are statins?
Statins are a type of medication that blocks the action of an enzyme in the liver that helps produce cholesterol. They are typically prescribed to lower blood cholesterol levels.Types of statins include:
Atorvastatin and rosuvastatin are the most potent while fluvastatin is the least potent. These medicines are sold under several different brand names, including Lipitor (an atorvastatin), Pravachol (a pravastatin), Crestor (a rosuvastatin), Zocor (a simvastatin), Lescol (a fluvastatin), and Vytorin (a combination of simvastatin and ezetimibe). Mevastatin is a naturally occurring statin found in red yeast rice.
Research into statins over the last few years has uncovered additional benefits, other than those based on cardiovascular outcomes. For instance, researchers from the Mayo Clinic, MN, carried out a study demonstrating that statins might reduce people's risk of developing esophageal cancer (cancer of the gullet).
A report published in the journal Circulation: Cardiovascular Quality and Outcomes concluded that overall, the benefits of statins largely outweigh the risks associated with the medication.
How do statins work?
Statins work by inhibiting a specific enzyme in the liver.
Statins inhibit an enzyme called HMG-CoA reductase, which controls cholesterol production in the liver.
The medicine blocks the active site of the enzyme, preventing other molecules from activating it, thereby slowing down the cholesterol production process.
Additional enzymes in the liver cell sense that cholesterol production has decreased and respond by creating a protein that leads to an increase in the production of LDL (low-density lipoprotein, or "bad" cholesterol) receptors.
These receptors relocate to the liver cell membranes and bind to passing LDL and VLDL (very low-density lipoprotein). The LDL and VLDL then enter the liver and are digested.
People often begin statin treatment to lower their cholesterol level to below 5 millimoles per liter, or by 25-30 percent. The dosage may be increased if this target is not reached. Treatment with statins usually continues even after the target cholesterol level is reached to continue the protection against atherosclerosis.
Who takes statins?
Statins are usually prescribed for individuals with the following conditions:
- Atheroma-related diseases such as heart disease and atherosclerosis. Statins reduce the chance that these conditions will worsen and can delay their progression
- Diabetes or another disease that increases the risk of developing an atheroma-related disease
- A family history of heart attacks (especially at a young age)
- Increasing age
A high cholesterol level is the most common reason that a person is prescribed statins, but the drugs also reduce heart diseases by preventing atherosclerosis. In fact, it is possible to have a heart attack without high blood cholesterol levels, but nearly all heart attacks begin with atherosclerosis plaque buildup.
Plaques from atherosclerosis can still form even when blood cholesterol is low. Therefore, statins may be used to treat people who already have atherosclerosis or are at a higher risk of developing it, even if they do not have high cholesterol levels.
Statins plus exercise usually better than statins alone
Researchers from the Veterans Affairs Medical Center, Washington DC, published a paper in The Lancet titled "Interactive effects of fitness and statin treatment on mortality risk in veterans with dyslipidaemia: a cohort study."
They found that for people with dyslipidemia (irregular levels of dangerous cholesterol/blood fats), the combination of taking statin medications and doing exercise is usually more effective in preventing early death than either intervention alone.
Exercise alone, however, for those with dyslipidemia, is better than taking no statin and doing no exercise. The authors found that those who do not take statins but are physically fit are half as likely to die an early death compared with unfit people with dyslipidemia who take no medication.
Side effects of statins
Individuals with liver disease should avoid statins.
Although most people who take statins have minor or no side effects, many can suffer from headache, pins and needle sensations, abdominal pain, bloating, diarrhea, feeling sick, and a rash.
The two most serious side effects - both of which occur relatively rarely - are liver failure and skeletal muscle damage.
The muscle damage is a severe type of myopathy called rhabdomyolysis.
Rhabdomyolysis usually begins as muscle pain and can worsen to such an extent that the patient loses all muscle cells, experiences kidney failure, or dies.
The condition is more common when statins are used in combination with other drugs that carry high rhabdomyolysis risk, or with other drugs that raise the statin levels in the blood.
People with active liver disease should not take statins. If liver disease develops while taking statins, usage should be stopped. Also, pregnant and breast-feeding women, or those intending to become pregnant, should not take statins.
It is generally recommended that people taking statins should not combine them with the following medications:
- Protease inhibitors (AIDS treatment)
- Fibrate drugs (that also lower LDL levels)
Some statin drugs may impair memory - researchers at the University of Bristol in England found that two commonly prescribed statins - pravastatin (Pravachol) and atorvostatin (Lipitor) - reduced performance of recognition and working memory in an animal experiment.
Statins may also raise the risk of developing cataracts. A research team at the San Antonio Military Medical Center, TX, reported in JAMA Ophthalmology that statin usage increased the risk of cataracts by 27 percent.
People who are taking statins should avoid grapefruits and grapefruit juice due to the potentially dangerous effects of an interaction.
Statins may slow down the aging process
Researchers at the Second University of Naples, Italy, found that statins may slow aging. Statins may reduce the rate at which telomeres shorten. Telomeres are tails of repetitive DNA sequences at the ends of a chromosomes; they protect the code from deterioration.
As we get older, telomeres get shorter, limiting the number of cells that can divide; this causes cellular aging.
In a study involving 203 participants, the researchers found that those who were taking statins had higher levels of telomerase activity in their white blood cells, resulting in less telomere shortening, compared with those not taking statins.
Lead researcher, Giuseppe Paolisso, said "By telomerase activation, statins may represent a new molecular switch able to slow down senescent cells in our tissues and be able to lead healthy lifespan extension. If it is confirmed that statins might actually slow aging itself, and not just the symptoms of aging, then statins are much more powerful drugs than we ever thought."
For more information on the harms and benefits of statins, see our article: Are Statins Good Or Bad?