Cape Gazette

People's Pharmacy

Food and drug interactions can be deadly

By Joe and Teresa Graedon | Aug 16, 2012

It all began with cheese. Doctors didn't think very much about the possibility that drugs might interact with foods until one man had cheese and crackers for supper. This turned out to be a deadly dining choice.

This 40-year-old fellow had been diagnosed with depression a month earlier in September, 1963. His doctor had prescribed a then-new drug called tranylcypromine (Parnate). One evening he'd complained of a slight headache but still had supper with his family: beef casserole, crackers and cheese. (The cheeses were Danish blue, Cheddar and a local Welsh specialty, Caerphilly.)

He felt worse during the night, with a horrible headache and nausea, but was convinced to try some breakfast--which included more cheese. He became agitated and confused and suffered a nosebleed and high fever. His family took him to the hospital where his blood pressure and pulse were both found to be extremely high.

In those days, doctors had never seen a case like his. They were not able to save his life, and he died at 8:30 p.m .that evening. They later determined that the interaction between his antidepressant medicine and the cheese had caused his death (The Lancet, May 16, 1964).

Food and drug interactions are now recognized as a serious problem. The trouble is that physicians and pharmacists are so busy that they may not have time to alert patients to the proper way to take medicine and which foods to avoid.

As a result, many people use their favorite beverage to swallow pills without considering the impact on drug absorption. Fruit juices are breakfast staples. Yet taking a blood pressure medicine like atenolol or an antibiotic such as ciprofloxacin with a large glass of OJ could dramatically reduce the amount of medicine that gets into circulation (British Journal of Clinical Pharmacology, Nov. 2010). In this case the drugs might not work as expected.

The same may hold true for grapefruit and thyroid medicine (Levothroid, levothyroxine, Levoxyl, Synthroid). More worrisome is the impact of grapefruit juice on the cancer drug etoposide (Vepesid). A modest amount of juice could cut availability of this life-saving drug in half.

The actions of grapefruit are complicated. It can raise blood levels of dozens of medications including cholesterol-lowering drugs like atorvastatin, lovastatin and simvastatin. The heart medicine amiodarone as well as the narcotic pain reliever oxycodone are also affected. This can result in unanticipated side effects.

To learn more about the impact of grapefruit and other foods on medicine, we offer our Guides to Drug, Food and Grapefruit Interactions.

Even something as healthy as fiber may interfere with drug absorption. Medications as varied as the heart drug digoxin, the antidepressant desipramine or the diabetes medicine metformin are all affected by taking them together with fiber such as oat bran, bran muffins or even guar gum found in low-fat salad dressings or frozen yogurt.

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