I am writing in response to your recent article entitled, “Preventing adverse grapefruit-drug interactions” [June, p. 89], which discussed potential drug interactions with grapefruit and its juice. Although it is important for people to be aware of potential interactions, we are concerned that statements that were made in this article do not correctly reflect the current medical and scientific understanding of this topic.

First, we know of no validated evidence that coadministration of grapefruit or its juice with a drug has caused a drug interaction resulting in actual harm to a patient’s health.

In addition, we are concerned with the article’s statement that 85 drugs have the possibility of interacting with grapefruit. Published studies indicate that clinically relevant interactions have only been reported for 13 of these medications.

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Further, we are concerned that your suggestion that the potential for an interaction lasts three to seven days after consumption may have misled readers, as scientific research suggests that the potential for an interaction lasts no more than 72 hours after consuming grapefruit.

Lastly, the cholesterol-lowering statin drugs pravastatin, fluvastatin, and rosuvastatin are considered to be safe to consume with grapefruit and its juice. 

Similarly, the blood pressure medications amlodipine, verapamil, and diltiazem are considered to be safe to consume with grapefruit and its juice. While this may sound like a fine point, it affects millions of people taking heart medications.

In an article in the Journal of Clinical Pharmacology, Hartmut Derendorf, PhD, and colleagues reported that:

  1. While some prescription medications may interact with grapefruit juice, most do not.

  2. For patients who are prescribed a medication that may interact with grapefruit juice and wish to continue consuming this healthy beverage, their physicians often can prescribe noninteracting, alternative medications within the most commonly prescribed drug classes. These medications often can provide the same therapeutic effect with no need to avoid grapefruit juice.

  3. It is safe to consume grapefruit juice while taking virtually all OTC medications.

Patients should consult with their physician or pharmacist if they have any questions about their prescription medication(s). After all, food and drug interactions, when they do occur, can vary by individual and prescription type. Our hope is to help clear up confusion around this issue and set the record straight that grapefruit juice can be safely co-ingested with the great majority of medications.

We encourage you to visit www.DrugInteractionCenter.org, which provides a continually updated listing of drugs that are known to interact with grapefruit and the level of interaction, along with access to cited scientific documentation. — MICHAEL D. SCHADLER, Director, Florida Department of Citrus, Bartow, Fla. (202-5)

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