A risky mix: Meds and grapefruit

More than two decades ago, a group of Canadian researchers studying a blood pressure drug gave grapefruit juice to their study subjects. Then they noticed something strange.

The juice did more than make people pucker. It actually jacked up the levels of the drug in the bodies of the participants.

The ramifications of their discovery are now well-known. Grapefruit juice -- and grapefruit itself -- can potentially interact with dozens of medications and cause all sorts of problems by increasing their effects. Other juices could spell trouble, too.

"If you are a grapefruit juice consumer, you should tell your health-care practitioners that you drink grapefruit juice so they can see if there is an interaction. It's something that they should be aware of," said Miriam Ellison, a clinical pharmacist at Good Samaritan Hospital Medical Center in West Islip.

A wide range of drugs can be affected by grapefruit or grapefruit juice, including frequently prescribed medications to lower cholesterol, lower blood pressure or fight bacterial infections, said Jeannene Strianse, director of pharmacy at Stony Brook University Hospital (see list below).

The effects of grapefruit interactions can be serious and have included death.

MEDICATION BUILDUP

What makes grapefruit such a potential villain is that it contains a substance that can disable proteins in the stomach and intestines. "These proteins help to metabolize -- or break down -- certain medications so that your body can properly rid itself of them," Strianse said. "When these proteins are inhibited by grapefruit or grapefruit juice, metabolism of the medication is slowed down and the medication can build up in the bloodstream."

Ellison warned against trying to avoid an interaction by taking your pills hours after you eat grapefruit or drink grapefruit juice. The problem, she said, is that the effects last for 24 to 72 hours.

And don't assume that the warnings are overblown if nothing weird happens after someone you know combines grapefruit and their pills. "People metabolize medication at different rates, and therefore it may affect some more than others," said Marcelle Levy-Santoro, administrator of pharmacy services at Nassau University Medical Center in East Meadow. "The degree of the effect varies widely between individuals and among the actual concentrations of the grapefruit juice. One grapefruit will have a slightly decreased effect than a full glass of juice since the juice is more concentrated than the actual fruit."

But what if you really are attached to your morning grapefruit or grapefruit juice? "The best advice to patients who do not want to give up the consumption of grapefruit juice is to discuss this issue with their physician, who can do one of two things: decrease the dose of the medication or change the medication to a different class that is not metabolized by this enzyme," Levy-Santoro said.

PROBLEMS WITH OTHER FRUIT

Grapefruit isn't alone on the risk list. The pomelo, a fruit that's similar to grapefruit, may have the same effects on medications, Strianse said.

Orange and apple juice could spell trouble, too: A 2008 study found that they disrupted levels of the allergy drug Allegra (fexofenadine).

Cranberry juice has been linked to problems with the blood thinner Coumadin (warfarin), although some pharmacists are skeptical.

The List

Medications known to be affected by grapefruit include:

Drugs that treat high cholesterol: Lipitor (atorvastatin), Mevacor (lovastatin) and Zocor (simvastatin)

Calcium channel blockers that are used to treat high blood pressure and control chest pain: Norvasc (amlodipine), Cardizem (diltiazem), Procardia (nifedipine) and Calan (verapamil)

Immunosuppressants, which help prevent rejection of a transplanted kidney, liver or heart: Neoral and Sandimmune (both cyclosporine) and Prograf (tacrolimus)

Drugs that treat certain bacterial infections: Erythromycin (sold under various brand names)

Certain anti-anxiety drugs used to relieve anxiety, control seizures and to relieve muscle spasms: Valium (diazepam)

An anti-anxiety drug often given to children before medical procedures to make them sleepy and prevent them from remembering what happened: Versed (midazolam syrup)