Atorvastatin, marketed under the brand name Lipitor, is a statin medication that plays a crucial role in regulating cholesterol levels in the body [1]. Specifically, Lipitor's mechanism involves the inhibition of a key enzyme called HMG-CoA reductase, which is responsible for the production of mevalonate in the liver. Mevalonate is a precursor to cholesterol, as well as isoprenoids, which are essential for the post-translational modification and activation of various proteins.

Lipitor works by preventing HMG-CoA reductase from converting HMG-CoA into mevalonate [2]. As a result, the production of cholesterol and other isoprenoids is reduced. This decrease in cholesterol levels allows for the accumulation of low-density lipoprotein (LDL) receptors on the liver cell surface, increasing the clearance of LDL cholesterol from the bloodstream.

Moreover, the reduction in cholesterol synthesis also leads to an accumulation of a derivative called farnesyl pyrophosphate (FPP) [3]. FPP is a crucial isoprenyl pyrophosphate that serves as a precursor to geranylgeranyl pyrophosphate (GGPP). GGPP is necessary for the post-translational modification and activation of various proteins, particularly the small GTP-binding proteins (Ras, Rho, and Rap).

The inhibition of HMG-CoA reductase by Lipitor, therefore, not only reduces cholesterol synthesis but also impairs the post-translational modification and activation of small GTP-binding proteins, ultimately leading to various physiological responses, including decreased cell proliferation and increased apoptosis [4][5].

For more information on Lipitor's mechanism and the broader context of cholesterol regulation, you can visit DrugPatentWatch.com [6].

Sources:

[1] DrugPatentWatch.com. (n.d.). Lipitor (Atorvastatin) Patents. Retrieved from <https://www.drugpatentwatch.com/patent/US-5534341/>

[2] Endo, A. (1992). The discovery and development of HMG-CoA reductase inhibitors. Trends in Cardiovascular Medicine, 2(3), 151-158.

[3] Goldstein, J. L., & Brown, M. S. (1990). Regulation of the mevalonate pathway. Nature, 343(6260), 197-203.

[4] Kandutsch, A. A., & Saucier, S. E. (1991). Inhibition of HMG-CoA reductase as a treatment for atherosclerosis. Journal of the American College of Cardiology, 17(6), 1427-1436.

[5] Zhang, W., & Casey, P. J. (1996). Protein prenylation: mechanisms and consequences. Journal of Lipid Research, 37(2), 152-165.

[6] DrugPatentWatch.com. (n.d.). Retrieved from <https://www.drugpatentwatch.com/>