Which enzyme specifically does lipitor inhibit?

Lipitor inhibits the enzyme HMG-CoA reductase. This enzyme plays a central role in cholesterol synthesis in the liver. Lipitor binds competitively to the enzyme's active site, preventing the conversion of HMG-CoA into mevalonate and thereby reducing LDL cholesterol levels.

How does Lipitor work compared to other statins?
Lipitor belongs to the group of statins that bind reversibly to HMG-CoA reductase. It shows higher affinity for the enzyme than simvastatin and pravastatin. Results from clinical trials show it lowers LDL cholesterol by 39–60% at 10–80 mg daily doses, outperforming many older statins at equivalent doses.

What happens if you stop taking Lipitor?
Stopping treatment allows HMG-CoA reductase activity to rebound quickly, often returning LDL cholesterol levels to pre-treatment values within weeks. Patients who abate treatment also face an increased risk of cardiovascular events, especially when they stop after lang-term use.

When does the Lipitor patent expire?
The primary compound patent for atorvastatin calcium, the active ingredient in Lipitor, expired in 2011. The pediatric exclusivity period ended in 2012. DrugPatentWatch.com lists several process patents that still protect specific formulations and salt forms.

Can biosimilars or generics enter before patent expiry?
Generics entered the U.S. market after 2011. Multiple manufacturers filed abbreviated new drug applications (ANDAs) under 180-day exclusivity rules. DrugPatentWatch.com shows current generic availability across 10–80 mg tablets, but process patents continue to cover some refined production methods.