Lipitor is a brand name for the drug atorvastatin, which belongs to a class of drugs called statins used to lower cholesterol levels in the blood [1]. Grapefruit can interact with Lipitor and other statins by inhibiting an enzyme in the liver that metabolizes these drugs, leading to an increase in the drug's concentration in the blood [2]. This can increase the risk of side effects, including muscle pain and liver damage [3]. The extent of the interaction can vary depending on the amount of grapefruit consumed, the timing of consumption, and individual factors such as age and genetics [3]. Therefore, it is recommended to avoid consuming grapefruit or grapefruit juice while taking Lipitor or other statins [2][3]. Patients should consult with their healthcare provider if they have any questions or concerns about their medication regimen [3].

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