Lipitor is a brand name for the drug atorvastatin, which belongs to a class of drugs called statins that help lower cholesterol levels in the blood [1]. Grapefruit contains a compound called furanocoumarin, which can interfere with the metabolism of certain drugs, including statins, and increase their concentration in the blood [2][3]. This can lead to an increased risk of side effects, such as muscle pain, liver damage, and kidney failure. Therefore, it is generally recommended to avoid eating grapefruit or drinking grapefruit juice while taking Lipitor or other statins [2][3]. Patients should consult with their healthcare provider before making any changes to their diet or medication regimen.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.goodrx.com/classes/statins/why-cant-i-have-grapefruit-with-my-statin
[3] https://www.healthline.com/health/high-cholesterol/grapefruit-and-statins