Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the body. If a person has stopped taking Lipitor, it is possible to restart the medication, but it is important to consult a healthcare provider before doing so.

According to Drug Patent Watch [1], Lipitor's patent expired in 2011, and the medication is now available as a generic drug. The expiration of the patent has made the medication more affordable and accessible to people who need it.

A study published in the British Medical Journal [2] found that restarting statin therapy, including Lipitor, after discontinuation was associated with a reduced risk of cardiovascular events. However, the study also found that the risk of adverse effects, such as muscle pain and liver damage, increased with the duration of statin therapy.

The National Center for Biotechnology Information [3] states that when restarting Lipitor, the dosage should be based on the patient's cholesterol levels and medical history. It is also important to monitor liver function and muscle pain while taking the medication.

In conclusion, Lipitor can be restarted after stopping use, but it is important to consult a healthcare provider before doing so. The dosage should be based on the patient's medical history and cholesterol levels, and liver function and muscle pain should be monitored while taking the medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.bmj.com/content/353/bmj.i3305
[3] https://www.ncbi.nlm.nih.gov/books/NBK548236/