Lipitor is a medication used to lower cholesterol levels in the blood and reduce the risk of heart disease and stroke. According to the drug patent watch [1], Lipitor (atorvastatin) was approved by the FDA in 1996. The time it takes to see results from Lipitor can vary depending on the individual's cholesterol levels and other factors such as diet and exercise. However, a study published in the Arteriosclerosis, Thrombosis, and Vascular Biology journal [2] found that significant reductions in LDL cholesterol (often referred to as "bad" cholesterol) were observed within two weeks of starting Lipitor therapy. The study also found that patients who continued to take Lipitor for six months experienced a further reduction in LDL cholesterol levels. Another study published on PubMed [3] found that Lipitor was effective in reducing LDL cholesterol levels in patients with hypercholesterolemia after four weeks of treatment. However, it is important to note that individual results may vary, and Lipitor should only be taken under the guidance of a healthcare professional.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ahajournals.org/doi/full/10.1161/01.atv.15.5.678
[3] https://pubmed.ncbi.nlm.nih.gov/16226162/