Lipitor is a brand name for atorvastatin, a medication used to treat high cholesterol levels. According to Drug Patent Watch [1], the patent for Lipitor expired in 2011, and since then, many generic versions of atorvastatin have become available. While the active ingredient in both brand name and generic versions of atorvastatin is the same, the inactive ingredients can differ, which may affect the medication's effectiveness.

According to Medical News Today [2], Lipitor works by blocking an enzyme in the liver that produces cholesterol. The medication is typically taken once a day, and its effects can be seen within two weeks of starting treatment. However, the article notes that if Lipitor is not taken regularly, its effectiveness may be reduced.

Additionally, the Mayo Clinic [3] notes that while statins like Lipitor are generally safe and effective, some people may experience side effects such as muscle pain, liver damage, and digestive problems. If these side effects occur, a healthcare provider may recommend a different medication or a lower dose of Lipitor.

In summary, while Lipitor can be an effective medication for treating high cholesterol levels, its effectiveness may be reduced if it is not taken regularly. Additionally, some people may experience side effects that can affect their ability to take the medication. It is important to talk to a healthcare provider about any concerns regarding Lipitor's effectiveness or potential side effects.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.medicalnewstoday.com/articles/lipitor
[3] https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/statin-side-effects/art-20046013