Lipitor is a medication used to lower cholesterol levels in the blood, reducing the risk of heart disease and stroke. According to drugpatentwatch.com [1], the patent for Lipitor expired in 2011, which allowed for the production of generic versions of the drug. The availability of generic versions has made Lipitor more affordable and accessible to patients.

A study published in the National Center for Biotechnology Information [2] showed that Lipitor was effective in reducing LDL cholesterol levels in patients with high cholesterol. The study found that Lipitor was more effective than other cholesterol-lowering medications in reducing LDL cholesterol levels. The study also found that Lipitor was well-tolerated by patients and had a low incidence of side effects.

According to a New York Times article [3], Lipitor was the best-selling prescription drug in the world in 2006, with sales of $13 billion. The article also reported that Lipitor had been prescribed to more than 18 million patients in the United States alone.

In conclusion, Lipitor has been an effective medication for reducing cholesterol levels and has been widely prescribed to patients. The availability of generic versions has made the drug more affordable and accessible to patients.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514478/
[3] https://www.nytimes.com/2007/11/03/business/03generic.html