Statins are a class of medicines that are frequently used to lower blood cholesterol levels. The drugs are able to block the action of a 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.
- Statins are used to lower cholesterol levels in the blood
- There are many types of statins, including mevastatin, pitavastatin and pravastatin
- Statins might also help with other diseases, for instance, preventing certain cancers
- Statins work by inhibiting an enzyme called HMG-CoA reductase
- People with atheroma-related disease, diabetes and a family history of heart attacks are often prescribed statins
- Exercising while taking statins is more effective than taking statins alone for people with dyslipidemia
- Side effects of stains can include diarrhea, bloating and rashes
- People with liver disease should avoid statins
- Some statins appear to impair memory in some circumstances.
What are statins?
Statins are a type of medication that block the action of a chemical in the liver that helps produce cholesterol. Statins 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 that is found in red yeast rice.
Research over the last few years has uncovered other benefits linked to statins, apart from cardiovascular ones. Researchers from the Mayo Clinic carried out a study that found that statins may 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 medicines actually act to replace the HMG-CoA that exists in the liver, 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.
Many people who begin statin treatment do so in order to lower their cholesterol level to less than 5 mmol/l, or by 25-30%. The dosage may be increased if this target is not reached. Treatment with the statin usually continues even after the target cholesterol level is reached in order to sustain atherosclerosis prevention.
On the next page, we look at who takes statins and the potential side effects of using these drugs.