HMG-CoA reductase

Class

Statin (HMG-CoA reductase inhibitor)

Pathway

Inhibits hepatic cholesterol biosynthesis, upregulates LDL receptor expression

HMG-CoA reductase is an enzyme anchored in the membrane of the endoplasmic reticulum in liver cells, where it catalyzes the rate-limiting step of the mevalonate pathway, the biochemical route by which the body synthesizes cholesterol. Drugs that inhibit this enzyme, known as statins, reduce the liver's internal cholesterol production. Because the cell continuously requires cholesterol for membrane structure and hormone synthesis, this reduction triggers a compensatory response: the liver increases the number of low-density lipoprotein (LDL) receptors on its cell surface. These receptors pull circulating LDL cholesterol, often called 'bad cholesterol,' out of the bloodstream, lowering overall LDL levels. This mechanism is central to cardiovascular disease prevention, since elevated LDL cholesterol is a well-established driver of atherosclerosis, the buildup of fatty plaques within artery walls that can lead to heart attack and stroke. By lowering circulating LDL, statins address one of the most modifiable risk factors for these conditions. The mechanism is broadly relevant across primary prevention in patients with elevated cholesterol and secondary prevention in those who have already experienced a cardiovascular event, and it remains one of the most extensively studied approaches in cardiovascular pharmacology, given the direct causal link between LDL cholesterol and arterial disease.