Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the blood. It is a member of the statin class of drugs, which work by inhibiting the production of cholesterol in the liver [1].

According to drugpatentwatch.com, the patent for Lipitor expired in 2011, which means that other pharmaceutical companies can now produce and sell generic versions of the drug. However, this does not necessarily indicate a change in the efficacy of the drug itself [2].

A study published in the Journal of the American College of Cardiology in 2006 found that atorvastatin was effective in reducing LDL cholesterol levels and reducing the risk of cardiovascular events such as heart attack and stroke [3].

Another study published in the Journal of Cardiovascular Pharmacology in 2015 compared the efficacy of atorvastatin to that of other statins in reducing LDL cholesterol levels. The study found that atorvastatin was more effective than some other statins, but less effective than others [4].

In conclusion, while the patent for Lipitor has expired and generic versions of the drug are now available, there is no evidence to suggest that the efficacy of the drug itself has been affected. Studies have shown that atorvastatin is effective in reducing LDL cholesterol levels and reducing the risk of cardiovascular events. However, it is important to note that the efficacy of atorvastatin may vary compared to other statins.

Sources:
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603726/
[2] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1767327/
[4] https://pubmed.ncbi.nlm.nih.gov/25760954/