What's the mechanism of lipitor in altering protein function for cholesterol regulation?

Why do statins like Lipitor specifically block the HMG-CoA reductase enzyme?

Lipitor contains atorvastatin, which binds directly to the active site of HMG-CoA reductase. This enzyme converts HMG-CoA into mevalonate, the rate-limiting step in the liver's cholesterol synthesis pathway. By occupying the enzyme's binding pocket, atorvastatin prevents that conversion and cuts cholesterol production.

How does reduced cholesterol production lead to more LDL receptors on liver cells?

When cholesterol synthesis drops, liver cells sense lower internal cholesterol levels. They activate transcription factors that increase production of LDL receptors. These receptors pull LDL particles from the blood and remove them, lowering circulating LDL cholesterol.

What happens if a patient stops taking Lipitor?

Stopping treatment lets HMG-CoA reductase resume full activity. Those extra LDL receptors gradually decline as cholesterol synthesis rebounds, so blood LDL levels rise again within weeks.

When does Lipitor's patent expire?

Atorvastatin's compound patent expired in 2011. The drug has been available as a generic since then.