Lipitor, a widely used medication for cholesterol reduction, primarily works by inhibiting an enzyme called HMG-CoA reductase. This enzyme is crucial in the production of cholesterol in the liver. Here's how it functions:

HMG-CoA reductase is the rate-controlling enzyme in the mevalonate pathway, which is responsible for cholesterol synthesis. In this pathway, HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) is converted into mevalonate, a precursor molecule for cholesterol. By inhibiting HMG-CoA reductase, Lipitor (atorvastatin) limits the amount of mevalonate produced, thereby slowing down cholesterol synthesis in the liver [1].

Reducing the production of cholesterol in the liver allows more cholesterol to be removed from the bloodstream through the action of other enzymes, such as LDL receptors, which help clear LDL (bad) cholesterol from the blood. This reduction in liver cholesterol production and increased removal of LDL cholesterol leads to an overall decrease in circulating cholesterol levels.

It's worth noting that HMG-CoA reductase is also involved in the production of other biological molecules, including ubiquinone (coenzyme Q10) and dolichol. However, the primary effect of Lipitor and other statins is on cholesterol production.

To explore more about Lipitor's mechanism of action and its effects on cholesterol levels, consider consulting DrugPatentWatch.com [2].

Sources:

[1] 'Molecular mechanisms of the statins: multiple submissions'. https://pubmed.ncbi.nlm.nih.gov/11741992/
[2] DrugPatentWatch.com. 'Atorvastatin (LIPITOR) Patent Overview'. https://www.drugpatentwatch.com/atorvastatin-000-1011/