Lipitor and Grapefruit

Studies have found that the combination of Lipitor (atorvastatin calcium) and grapefruit or grapefruit products can cause serious interaction side effects. Occurrences of severe muscle pain, fatigue, and fever have been reported, as well as medical conditions that may lead to kidney failure. 

The adverse interaction between Lipitor and grapefruit is attributed to properties in grapefruit that inhibit CYP 3A4, an essential enzyme found in the intestinal wall tract. CYP 3A4 plays an essential and critical role in breaking down medications, including Lipitor, in the body. When the efficacy of this enzyme is compromised, it can produce harmful side effects. Informal testing of interactions between grapefruit and a blood pressure medication resulted in blood levels four times higher than recommended. The compound in grapefruit responsible for adverse interactions with Lipitor and other medications remains a mystery, but it is believed it may be a bioflavinoid, the same as that which lends grapefruit its distinctive taste. 

Dubbed the "grapefruit effect", the adverse interaction was first discovered in the 1990s. Further research has indicated that this interaction can be highly variable, and is in point dependent upon the amount of CYP 3A4 already present in an individual's intestinal tract. This can differ drastically from one individual to the next, but those with high levels of the enzyme are the most susceptible to adverse reactions when combining Lipitor with grapefruit. At this time there exists no reliable platform for testing an individual for CYP 3A4 levels. Observations seem to indicate that older individuals are more susceptible to grapefruit and Lipitor adverse interaction. These reactions are not noted in individuals who receive their medication transdermally or by injection, as the CYP 3A4 enzyme is not involved in the breaking down of the medication. 

Adverse interaction between Lipitor and grapefruit is found in all grapefruit products including fresh grapefruit, grapefruit juice, and grapefruit supplements. The interaction produced from ingesting grapefruit can be long lasting, from 24 hours up to two days. 

If you are on Lipitor, you should avoid grapefruit and grapefruit products entirely to avoid any risks associated with this combination. Other citrus fruits such as oranges, have not been identified to have the same compound bioflavinoid as grapefruit, and do not appear to cause any adverse interaction. A specific type of orange, known as Seville orange, has been observed to cause an adverse reaction similar to grapefruit, and should be avoided. 

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