Use caution when mixing meds with grapefruit

We have a grapefruit on our kitchen counter right now. It’s a large, beckoning, ruby red version. I intend to cut it in half and use one of those clever little serrated-edge spoons to slowly dig out each segment and enjoy every juicy morsel. I’ll definitely squeeze out the leftover juice and slurp that down, too.

But if I were taking a statin drug (for high cholesterol), some of the medications prescribed for hypertension, some psychotropic medications (for a mental disorder) or even certain antihistamines, I would be a lot less inclined to indulge in that ruby red. In fact, I wouldn’t do it. Increasingly, research is showing the relationship between certain medications and grapefruit juice, even the grapefruit itself, can produce a significant adverse, even fatal, reaction.

Apparently, the problem was discovered quite by accident. Researchers were looking for possible interactions between blood pressure medications and alcohol and used grapefruit to mask the taste of the alcohol. They ultimately found that grapefruit juice dangerously increased the amount of the medication reaching the blood stream, creating a risk of toxicity.

With some medications there is already a "narrow therapeutic index," and certain individuals taking specific medications and drinking grapefruit juice too get into a danger zone very quickly. It doesn’t take much juice.

So what are the drugs that interact with grapefruit juice? I couldn’t find a single comprehensive list, but it was repeatedly noted that "the statins" and calcium channel blockers for high blood pressure frequently present problems.

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This issue has not been studied extensively; I really had to search for science-based information on it. My investigation unearthed a variety of explanations, but most experts think it results from one, or more, of the chemicals in the juice altering the activity of enzymes in the intestinal tract.

The unpredictability is what seems the most worrisome, as a vast number of drugs may be affected, some not yet identified, and the magnitude of the response in some patients is extreme. For more information, try the "Ask the Pharmacist" Web site operated by the University of Mississippi Medical Center at http://umcnews.com/.

Some clinicians are not as worried about this issue as others, although there have, reportedly, been more than 100 deaths nationwide. The less concerned sources suggest, "don’t ingest grapefruit juice two hours before and five hours after taking a drug with which you think it might interact." If you’re an older adult who drinks a full glass of calcium-fortified grapefruit juice with your morning medications, you might want to reconsider that approach. I understand your reluctance to quit; remember, I’m the one with that big fat fruit sitting on my kitchen counter, calling to me.

I’m better educated on this issue than when I began this column. And when you’re better informed, good decisions typically follow.

Here’s my plan. I’ll still scoop and slurp my awaiting fruit, but I’ll definitely stop bringing ruby reds to my medication-taking, grapefruit-loving mother. Definitely.

Sharon Johnson is an assistant professor in family and community development at OSU Extension and a member of the Senior Advisory Council. Reach her at s.johnson@oregonstate.edu.