Generic versions of Lipitor, a cholesterol-lowering medication, are available at a significantly lower cost compared to the brand-name drug. The price difference is primarily due to the expiration of Lipitor's patent, allowing other manufacturers to produce and sell the drug under generic names.

According to DrugPatentWatch.com [1], the patent for Lipitor (atorvastatin) expired in the United States on November 30, 2011. After the patent expiration, multiple generic manufacturers entered the market, leading to a decrease in the drug's price.

A study published in the Journal of Managed Care & Specialty Pharmacy [2] compared the prices of brand-name Lipitor and its generic alternatives. The study found that the average monthly retail price for brand-name Lipitor was $193.30, while the average monthly retail price for generic atorvastatin was $22.50. This represents a significant cost reduction of approximately 88%.

In addition, a report by the FDA [3] states that the availability of generic drugs increases competition, which often leads to lower prices for both brand-name and generic drugs. This competition helps drive down the cost of medications, making them more accessible to patients.

In summary, generic versions of Lipitor are widely available and significantly cheaper than the brand-name drug. The price difference is primarily due to the expiration of Lipitor's patent, which allowed other manufacturers to produce and sell the drug under generic names. According to DrugPatentWatch.com, Lipitor's patent expired in the United States on November 30, 2011.

Sources:
[1] <https://www.drugpatentwatch.com/drugs/lipitor>
[2] <https://www.jmcp.org/doi/full/10.18553/jmcp.2015.21.6.683>
[3] <https://www.fda.gov/drugs/generic-drugs/advantages-generic-drugs>