Lipitor is a brand name for the drug atorvastatin, which is a type of statin used to lower cholesterol levels in the body. According to Drug Patent Watch [1], Lipitor's active ingredient is atorvastatin calcium. Grapefruit juice is known to interact with some medications, including statins like Lipitor. GoodRx [2] explains that grapefruit juice can increase the amount of the drug that enters the bloodstream, leading to an increased risk of side effects. The Harvard Health Letter [3] states that grapefruit juice can cause the levels of Lipitor in the blood to rise, which can increase the risk of side effects such as muscle pain, liver damage, and kidney problems. Therefore, it is recommended to avoid consuming grapefruit juice or grapefruit products while taking Lipitor. Patients should consult their healthcare provider for further information and guidance regarding the use of Lipitor.

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.health.harvard.edu/heart-health/grapefruit-juice-and-statins