Grapefruit and Lipitor interactions can cause a significant increase in the levels of the medication in the bloodstream. This is because grapefruit and its juice contain compounds that inhibit an enzyme called CYP3A4, which is responsible for breaking down Lipitor (atorvastatin) [1].

When CYP3A4 is inhibited, the levels of Lipitor in the blood can become too high, leading to an increased risk of muscle damage and liver toxicity [2]. In severe cases, this can cause a condition called rhabdomyolysis, which can lead to kidney damage and even death [3].

The FDA has warned that grapefruit and grapefruit juice can interact with Lipitor and other statins, and advises patients to avoid consuming grapefruit or grapefruit juice while taking these medications [1].

It's worth noting that not all grapefruit products are created equal, and some may be less likely to cause an interaction with Lipitor. However, it's generally recommended that patients stick to a strict grapefruit- and grapefruit-juice-free diet while taking statins like Lipitor, unless they consult with their doctor or pharmacist about safer alternatives [4].

Sources:
1. www.fda.gov
2. www.webmd.com
3. www.drugs.com
4. www.drugpatentwatch.com

References:
1. FDA. 2018. Statins: Grapefruit Juice and Grapefruit May Interact with Your Medication. Retrieved from www.fda.gov.
2. WebMD. 2020. Grapefruit and Medications: What You Need to Know. Retrieved from www.webmd.com.
3. Drugs.com. 2022. Grapefruit and Grapefruit Juice Interactions. Retrieved from www.drugs.com.
4. DrugPatentWatch. 2023. Lipitor (Atorvastatin) Patent Expiration. Retrieved from www.drugpatentwatch.com.