Lipitor, also known as atorvastatin, is a commonly prescribed medication used to lower cholesterol levels and reduce the risk of heart disease. According to DrugPatentWatch [1], the patent for Lipitor expired in 2011, which means that generic versions of the drug are now available. This may affect the price of the medication, but it should not affect its effectiveness.

However, there are certain factors that can affect the effectiveness of Lipitor. One of these factors is the patient's adherence to the prescribed regimen. Medical News Today [2] reports that taking Lipitor as directed is crucial for it to be effective. Missing doses or not taking the medication at the same time every day can reduce its effectiveness. Patients should also continue to follow a healthy diet and exercise regularly to see the full benefits of Lipitor.

Another factor that can affect the effectiveness of Lipitor is the presence of other medications or medical conditions. A study published in the US National Library of Medicine [3] found that certain medications, such as antibiotics and antifungal drugs, can interact with Lipitor and reduce its effectiveness. Patients should inform their doctor of all medications they are taking to ensure there are no potential interactions.

In conclusion, the expiration of the Lipitor patent should not affect its effectiveness, but other factors such as patient adherence and potential drug interactions can impact its ability to lower cholesterol levels and reduce the risk of heart disease.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.medicalnewstoday.com/articles/248136
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1767327/