Lipitor, also known as atorvastatin, is a medication that is used to lower cholesterol levels in the body. According to Drug Patent Watch [1], the patent for Lipitor expired in 2011, which means that generic versions of the drug are now available. The effectiveness of the drug can vary depending on the individual, but it generally takes a few weeks to see a significant decrease in cholesterol levels [2].

As for how long Lipitor remains effective, it is important to note that the drug needs to be taken regularly in order to maintain its effectiveness. If someone stops taking the drug, their cholesterol levels may begin to increase again. However, according to Drugs.com [3], atorvastatin has a half-life of approximately 14 hours, which means that it can stay in the body for several days after the last dose.

It is important to note that Lipitor can have side effects, such as muscle pain and weakness, liver problems, and digestive issues [2]. If someone experiences any of these side effects or has concerns about the effectiveness of the drug, they should speak with their healthcare provider.

In conclusion, Lipitor can take a few weeks to become effective and needs to be taken regularly to maintain its effectiveness. Atorvastatin can stay in the body for several days after the last dose, but if someone stops taking the drug, their cholesterol levels may begin to increase again. It is important to speak with a healthcare provider about any concerns or side effects related to the use of Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.singlecare.com/blog/lipitor-side-effects/
[3] https://www.drugs.com/medical-answers/long-atorvastatin-stay-system-after-stopping-drug-527313/