Lipitor is a popular drug used to lower cholesterol levels in the body. The price of Lipitor can vary depending on several factors, including the manufacturer, dosage, and location. According to the sources provided, the price of Lipitor changes frequently due to a variety of reasons.

One factor that affects the price of Lipitor is the expiration of its patent. According to Drug Patent Watch [1], the patent for Lipitor expired in 2011, which allowed other manufacturers to produce generic versions of the drug. The introduction of generic versions of Lipitor has led to a decrease in the price of the drug. As of August 2021, the average retail price for a 30-day supply of atorvastatin (generic Lipitor) is $9.23, according to GoodRx [2].

Another factor that affects the price of Lipitor is the cost of research and development. According to US Pharmacist [3], drug companies invest a significant amount of money in research and development to bring new drugs to market. These costs are often passed on to consumers in the form of higher drug prices.

In conclusion, the price of Lipitor changes frequently due to several factors, including the expiration of its patent, the introduction of generic versions, and the cost of research and development. The average retail price for a 30-day supply of atorvastatin (generic Lipitor) is $9.23, as of August 2021, according to GoodRx [2].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.goodrx.com/atorvastatin/what-is
[3] https://www.uspharmacist.com/article/understanding-drug-pricing