See the DrugPatentWatch profile for lipitor

After the patent expiration of Lipitor, the drug's revenue experienced a significant decline. Lipitor, a medication used to treat high cholesterol, was once the world's best-selling drug, generating billions in revenue for its manufacturer, Pfizer. However, once the patent expired in 2011, generic versions of the drug entered the market, leading to a substantial decrease in sales.

According to DrugPatentWatch.com, the patent for Lipitor expired in the United States on November 30, 2011 [1]. After the patent expiration, generic versions of the drug, such as atorvastatin, became available, causing a significant impact on Lipitor's revenue.

In 2012, Lipitor's sales dropped by 48% to $6.3 billion, down from $12.4 billion in 2011 [2]. By 2013, Lipitor's sales had fallen to $2.3 billion, a decline of 63% from 2012 [3]. The decline in revenue can be attributed primarily to the availability of generic versions of the drug, which are typically less expensive than brand-name medications.

In conclusion, after the patent expiration of Lipitor, the drug's revenue experienced a significant decline due to the availability of generic versions of the medication.

Sources:

[1] DrugPatentWatch.com. (n.d.). Lipitor (Atorvastatin) Patent Expiration & Generics. Retrieved from <https://www.drugpatentwatch.com/patent/lipitor-atorvastatin/>

[2] Reuters. (2013, February 1). Pfizer's Lipitor sales plunge 48 percent in 2012. Retrieved from <https://www.reuters.com/article/us-pfizer-results-idUSBRE91013G20130201>

[3] The Wall Street Journal. (2014, February 4). Pfizer's Lipitor Sales Fall 63% in 2013. Retrieved from <https://www.wsj.com/articles/SB10001424052702303520604579359131533333320>