Statins
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1.Introduction:
The statins (or HMG-CoA reductase inhibitors) are a class of drugs that lower cholesterol levels in people with or at risk of cardiovascular disease.
They lower cholesterol by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting enzyme of the mevalonate pathway of cholesterol synthesis. Inhibition of this enzyme in the liver results in decreased cholesterol synthesis as well as increased synthesis of LDL receptors, resulting in an increased clearance of low-density lipoprotein (LDL) from the bloodstream. The first results can be seen after one week of use and the effect is maximal after four to six weeks.
2.Mechanism Of Action:
Statins act by inhibiting the enzyme HMG-CoA reductase, the enzyme controlling the first committed step of sterol (cholesterol) synthesis, in the liver. Because statins are similar to HMG-CoA on a molecular level they take the place of HMG-CoA in the enzyme and reduce the rate by which it is able to produce mevalonate, the next molecule in the cascade that eventually produces cholesterol, as well as a number of other compounds.
Inside the liver cell, other enzymes of the protease class sense the decreased level of cholesterol produced. In response, they cleave a protein called "membrane-bound sterol regulatory element binding protein", which then responds by migrating to the nucleus to increase production of various other proteins and enzymes, including the LDL receptor. The LDL receptor then relocates to the cell membrane of the liver cell, and binds to passing low density lipoprotein and very low density lipoprotein particles (both containing cholesterol in the undesired form). LDL and VLDL enter the liver and are digested.
3.cholesterol related actions:Statins exhibit action beyond lipid-lowering activity in the prevention of atherosclerosis. Researchers hypothesize that statins prevent cardiovascular disease via four proposed mechanisms:
1.Improve endothelial function
2.Modulate inflammatory responses
3.Maintain plaque stability
4.Prevent thrombus formation
4.Examples:Atorvastatin,Cerivastatin,Fluvastatin,Lovastatin,Mevastatin,Simvastatin etc.
5.Adverse Efeect:myalgias, muscle cramps,rhabdomyolysis.
Drug Interection:Combining any statin with a fibrate, another category of lipid-lowering drugs, increases the risks for rhabdomyolysis.
The statins (or HMG-CoA reductase inhibitors) are a class of drugs that lower cholesterol levels in people with or at risk of cardiovascular disease.
They lower cholesterol by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting enzyme of the mevalonate pathway of cholesterol synthesis. Inhibition of this enzyme in the liver results in decreased cholesterol synthesis as well as increased synthesis of LDL receptors, resulting in an increased clearance of low-density lipoprotein (LDL) from the bloodstream. The first results can be seen after one week of use and the effect is maximal after four to six weeks.
2.Mechanism Of Action:
Statins act by inhibiting the enzyme HMG-CoA reductase, the enzyme controlling the first committed step of sterol (cholesterol) synthesis, in the liver. Because statins are similar to HMG-CoA on a molecular level they take the place of HMG-CoA in the enzyme and reduce the rate by which it is able to produce mevalonate, the next molecule in the cascade that eventually produces cholesterol, as well as a number of other compounds.
Inside the liver cell, other enzymes of the protease class sense the decreased level of cholesterol produced. In response, they cleave a protein called "membrane-bound sterol regulatory element binding protein", which then responds by migrating to the nucleus to increase production of various other proteins and enzymes, including the LDL receptor. The LDL receptor then relocates to the cell membrane of the liver cell, and binds to passing low density lipoprotein and very low density lipoprotein particles (both containing cholesterol in the undesired form). LDL and VLDL enter the liver and are digested.
3.cholesterol related actions:Statins exhibit action beyond lipid-lowering activity in the prevention of atherosclerosis. Researchers hypothesize that statins prevent cardiovascular disease via four proposed mechanisms:
1.Improve endothelial function
2.Modulate inflammatory responses
3.Maintain plaque stability
4.Prevent thrombus formation
4.Examples:Atorvastatin,Cerivastatin,Fluvastatin,Lovastatin,Mevastatin,Simvastatin etc.
5.Adverse Efeect:myalgias, muscle cramps,rhabdomyolysis.
Drug Interection:Combining any statin with a fibrate, another category of lipid-lowering drugs, increases the risks for rhabdomyolysis.
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