Lipitor is a medication used to lower cholesterol levels in the blood. According to the drug patent watch website [1], the active ingredient in Lipitor is atorvastatin calcium, which works by inhibiting the production of cholesterol in the liver. A study published in the New England Journal of Medicine [2] found that taking Lipitor with food did not significantly affect its effectiveness in lowering cholesterol levels. However, the study did note that taking Lipitor with a high-fat meal may delay the medication's absorption, which could lead to a delay in its onset of action. Additionally, a Reuters article [3] suggests that taking Lipitor with a high-fat meal may increase the risk of side effects such as muscle pain and liver damage. Therefore, it is generally recommended to take Lipitor on an empty stomach or with a low-fat meal to maximize its effectiveness and minimize the risk of side effects.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://pubmed.ncbi.nlm.nih.gov/8568017/
[3] https://www.reuters.com/article/us-burger-statin/burger-and-a-statin-to-go-or-hold-that-please-idUSTRE67C2GE20100813