Thoughts from a Lab Rat

I received this question anonymously from a fellow lab rat.

Q. What’s the big deal with grapefruit juice?

A. Nearly every study has a grapefruit product restriction. Why? Because it can interact with numerous medications and can be fatal.

Grapefruit juice, and grapefruit in general, is a potent inhibitor of the intestinal cytochrome P450 enzyme CYP3A4, which can impact the metabolism of a variety of drugs, increasing their bioavailability when administered orally. In some cases, this can lead to a fatal interaction with drugs like astemizole or terfenadine. The effect of grapefruit juice with regard to drug absorption was originally discovered in 1989. However, the effect became well-publicized after being responsible for a number of deaths due to overdosing on medication. However, the first published report on grapefruit drug interactions was in 1991 in the Lancet (British) entitled “Interactions of Citrus Juices with Felodipine and Nifedipine.” and was the first reported food-drug interaction clinically. (wikipedia)

There are many urban legends that have led people to believe that grapefruit juice is the “cleanse all” miracle cure. Smoke a joint before a drug test and swig a few glasses of grapefruit juice and you’ll piss cleaner than the day you were born. While I’m not here to confirm or deny whether or not that works, let’s just say it doesn’t. Sadly, it can have devastating consequences. Long story short, grapefruit juice prevents drugs from metabolizing correctly which means that the medication stays in the body longer than intended. In multiple doses, the medication will stockpile in the liver and can eventually lead to a drug overdose. Certainly there are many factors but in the end, clinics must eliminate as many factors that can effect a trial as possible. This is one major factor that you do not want to ignore.