List of drugs that interact with grapefruit juice growing

For years, researchers have known grapefruit juice negatively reacts with certain medications, producing serious and possibly life-threatening side effects for the patient.

The number of prescription drugs that interact with grapefruit juice is climbing, according to a recent study published in the Canadian Medical Association Journal. More than 85 drugs on the market, when consumed with a glass or more of grapefruit juice per day, are known to cause health problems.

"There's new medications all of the time that have this reaction, so we want to look out for that," said Brett Bieber, a clinical pharmacist at Mercy Medical Center.

According to Bieber, all drugs are tested for reactions to grapefruit before they hit the market.

He explained that enzymes in the intestines known as cytochromes break down drugs. Chemicals in grapefruit juice destroy or block these enzymes, so the body ends up absorbing more of the drug than it normally would.

"Enzymes in the intestines are what your body would normally use to help start breaking down drugs so you don't get as much affect out of it," he said. "Your body sees drugs as toxins, not normal to it, so it's trying to eliminate those."

The elderly, Bieber said, are at greatest risk because their bodies don't metabolize drugs as efficiently.

Eating an actual grapefruit, may not be that big of a deal, but Bieber said patients should be sure to check with their doctor or pharmacist before adding the citrus fruit to their diet if they are taking a prescription drug known to react with it.

Squirt, a carbonated soft-drink, contains grapefruit juice, as does Seville orange marmalade, according to Bieber. He said patients may also want to be wary of Pomelos, a tropical citrus fruit related to the grapefruit, which may also cause reactions.

Why are some drugs a problem when consumed with grapefruit juice and others not?

The body, according to Bieber, breaks down those other drugs with enzymes that grapefruit juice doesn't block or with other systems altogether.

Auxiliary labels, he said, are placed on prescription drug bottles to warn patients of the interaction.

Grapefruit juice in combination with cholesterol-lowering drugs Lipitor, Zocor and Mevacor can lead to Rhabdomyolysis, the breakdown of muscle fiber, and kidney damage. When consumed with pain relievers Oxycodone and Methadone, Bieber said it can slow down breathing.

Taking grapefruit juice with anti-anxiety medications Valium and Triazolam, Bieber said, will result in a morning "hangover effect."

An interaction between grapefruit and a prescription drug could even result in death, but Bieber said it is rare.

"That would be the extreme, extreme," he said. "The biggest problem that I think we caution patients about is usually with statins and blood pressure meds."