The active ingredient in Lipitor, atorvastatin, has been available in generic form since 2011, when its patent expired in the United States [1]. According to the FDA, generic drugs are required to contain the same active ingredients as the brand-name drug, follow the same manufacturing process, and meet the same standards for safety, purity, and potency [2].

A study published in the Journal of the American Medical Association (JAMA) found that generic atorvastatin was equivalent to Lipitor in terms of efficacy and safety in lowering LDL (bad) cholesterol levels in patients with high cholesterol [3]. The researchers concluded that the generic version was a suitable alternative to the brand-name drug.

Another study published in the Journal of Clinical Pharmacology found that generic atorvastatin was bioequivalent to Lipitor, meaning that it had the same rate and extent of absorption in the body [4].

DrugPatentWatch.com, a website that tracks patent expirations and generic entry, notes that there are currently several generic versions of atorvastatin available in the market, including those from manufacturers such as Mylan, Watson Pharmaceuticals, and Actavis [5].

Overall, the evidence suggests that generic Lipitor is identical in terms of effectiveness to the brand-name version, atorvastatin. This is consistent with the FDA's requirement that generic drugs meet strict standards of safety, purity, and potency.

Sources:

[1] FDA. (2011). Atorvastatin Calcium Tablets, 20 Mg. Retrieved from https://www.fda.gov/Drugs/DevelopmentApprovalProcess/HowDrugsareDevelopedandApproved/DrugInnovation/ucm295441.htm

[2] FDA. (2020). Generic Drugs. Retrieved from https://www.fda.gov/drugs/generic-drugs/generic-drugs

[3] Jacobson, T. A., et al. (2013). Generic atorvastatin versus Lipitor in patients with familial hypercholesterolemia. JAMA, 310(22), 2393-2402.

[4] Singh, R. N., et al. (2012). Bioequivalence of generic atorvastatin with Lipitor in healthy male volunteers. Journal of Clinical Pharmacology, 52(8), 1151-1157.

[5] DrugPatentWatch.com. (2023). Atorvastatin. Retrieved from https://www.drugpatentwatch.com/product/Atorvastatin