Grapefruit juice can decrease the potency of Lipitor, a medication used to lower cholesterol levels. According to Drug Patent Watch [1], Lipitor's active ingredient is atorvastatin calcium. Grapefruit juice contains furanocoumarins, which can interfere with the enzymes that break down atorvastatin calcium in the liver. This interference can lead to higher levels of the medication in the bloodstream, which can increase the risk of side effects.

The New York Times [2] explains that grapefruit juice can affect the metabolism of many medications, including Lipitor. Grapefruit juice inhibits the activity of the cytochrome P450 3A4 (CYP3A4) enzyme, which is responsible for breaking down many drugs, including atorvastatin. When this enzyme is inhibited, the body absorbs more of the medication, which can increase the risk of side effects.

GoodRx [3] recommends avoiding grapefruit and grapefruit juice while taking Lipitor to prevent interactions. They suggest that patients talk to their healthcare provider about any concerns they have about grapefruit and medication interactions.

In conclusion, grapefruit juice can decrease the potency of Lipitor, and patients should avoid consuming grapefruit or grapefruit juice while taking this medication to prevent potential interactions. It is important to talk to a healthcare provider about any concerns regarding medication interactions.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.nytimes.com/2006/03/21/health/experts-reveal-the-secret-powers-of-grapefruit-juice.html
[3] https://www.goodrx.com/classes/statins/why-cant-i-have-grapefruit-with-my-statin