What are Statins?
Statins are cholesterol lowering drugs and one of the most commonly prescribed drugs after antibiotics and pain killers. The group as a whole is known as “statins” as all of the drugs in this group have – statin as a suffix in the chemical name.
Various studies of the last two decades have conclusively proved the role of statins in the prevention of heart attack, stroke and other diseases related to high blood cholesterol levels. Statins not only decrease morbidity (incidence of disease occurrence), but also deaths from heart diseases.
How do the statins work?
Cholesterol and triglycerides are different forms of lipids in the body. Cholesterol is necessary for normal synthesis of cell membranes and hormones in the body. Triglycerides provides energy to the cells.
Cholesterol is carried by lipoproteins in the bloodstream, like LDL-C (Low Density Lipoprotein-Cholesterol). High levels of LDL-C are harmful as these particles are the main contributors to atherosclerotic plaques in the walls of the arteries. Refer to What is Atherosclerosis? HDL-C (High Density Lipoprotein-C), another lipoprotein is considered to be “good” cholesterol as it carries the cholesterol back from the blood into the liver.
Statins decrease the levels of total cholesterol and LDL-C (“bad cholesterol”) in the body. Statins inhibit the action of the enzyme HMG-CoA reductase (3-hydroxy- 3-methylglutaryl-coenzyme A) which leads to the synthesis of cholesterol in the liver. Therefore, statins are also referred as HMG-CoA reductase inhibitors. Statins also increase the uptake of LDL-C into the liver from the blood stream.
Action of Statins
By inhibiting the formation of cholesterol, statins decrease the levels of LDL-C in blood. This decreases the incidence of formation of new atherosclerotic plaques. Statins also have a modest effect on the triglyceride levels – it decreases triglycerides slightly and increases the HDL-C levels. Statins are also thought to have additional unrelated actions.
It is now being thought that statins increase the stability of plaques thus decreasing the chance of blood clot formation. These also decrease the inflammation in the arteries and oxidative stress (increased concentrations of free radicals). All of these effects collectively prevent the occurrence of heart attack.
Types of Statins
Alphabetically the statins can be arranged as:
All of these drugs have the same mechanism of action.
Atorvastatin, rosuvastatin and pitavastatin are given once daily whereas others have different regimens. Statins, except for atorvastatin and rosuvastatin, should be taken in the evening, if only single dose is to be taken in a day, as cholesterol is predominantly synthesized during night. All of these except pravastatin should be taken with food as the absorption is increased. The most efficacious statin is rosuvastatin.
Statins can be used in combination with other lipid-lowering drugs depending upon the lipid-profile of the patient or if a single statin is not sufficient to improve the lipid-profile. Statins may be used with other drugs and compounds as follows :
- with bile acid-resins, like cholestyramine, in patients with familial hypercholesterolemia,
- in combination with niacin (not the vitamin supplement) in patients with very high levels of triglycerides,
- in combination with ezetimibe in some patients with hypercholesterolemia.
The side effects of statins, like most oral medication, often involves the gastrointestinal tract. Muscle pain, liver damage and nerve pain (neuralgia) are among the other adverse effects that may be noted with prolonged or high doses of statins. These effects and others are discussed in Statins Side Effects.