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Food And Drug Interactions

Note: Our writer posed as a patient to see if pharmacists would fill a potentially harmful combination.

I tried to fill two phony prescriptions, just to prove a point.

One was for Seldane (terfenadine), a popular antihistamine. The other was for erythromycin, a widely used antibiotic. Each medication is safe by itself. Mixing them, however, can be deadly.

Every pharmacist should know this--without having to look it up. It's the classic example of two prescription drugs that should never be taken together, and one of the most publicized.

Erythromycin may cause blood levels of Seldane to increase; in rare cases, this can trigger fatal heart-rhythm abnormalities. The problem was discovered in 1990. Three times since, the maker of Seldane has sent warning letters to every doctor and pharmacist in the country. The latest batch was mailed last June. The letters would have been hard to miss. But, anyone who did miss them would have caught an earlier advisory from the Food and Drug Administration. The same message is also clearly printed with every Seldane package. So I really wasn't expecting anyone to fill my order.

The prescriptions were written by David Flockhart, M.D., as part of a study in collaboration with Georgetown University Medical Center. We wanted to see if I could find a pharmacist who'd actually dispense them. Unfortunately, it didn't take long.

The first two pharmacists I met turned me down. One was wild with disbelief, wondering why a doctor would write a potential death sentence. The other was incredulous. He shook his head and said, "I cannot in good conscience fill these."

But a third pharmacist, at a discount drugstore, obligingly filled the two scripts. He gave me two bottles of pills, counseling me to take the Seldane less frequently than prescribed.

Only at the last moment did the pharmacist see a warning on one bottle "I just realized there's a problem," he said, seizing the Seldane. "You can't take these together."

If he was careless, the next pharmacist must have been asleep. I dropped off my prescriptions. A half hour later, I picked them up, no questions asked. Turning to leave the small, independent drugstore, I asked, "Can I take these together?"

"Wait, you reminded me of something," said the pharmacist, now on high alert. "I think there's something about that." She scanned some literature. "No, you can't take them together. Don't take them together."

Back home, I stared at my prescriptions. My hands shook as I read the labels. Nothing warned me not to mix the drugs. If I were a real patient, I wouldn't have known my life could possibly be cut short by a prescription error.

I could have written this all off as a fluke, two bad pharmacies in a sea of others with impeccable standards. But I found yet another pharmacist, this time in an upscale supermarket, willing to fill my request. Only after filling them did he notice the computerized printout warning of a dangerous interaction.

In all, I visited seven pharmacies near my home in central Massachusetts. Four pharmacists would not. fill my order, but one druggist did, and two others were thwarted only by computer programs.

Computer programs that flag interactions are standard in any well-run pharmacy. But how much protection do they offer?

Not much, according to another study by Dr. Flockhart's colleagues. They tried a similar experiment. Visiting 50 pharmacies in the Washington, D.C., area, the researchers found that 32 percent of pharmacists didn't warn patients that erythromycin and Seldane should not be mixed.

All but two of these drugstores had computer programs in place. Even so, 29 percent of pharmacists with access to this technology either didn't see the alert or didn't pass along the news to their customers.

The results were alarming, even to the Georgetown University research team that conducted the study. "None of us dreamt that pharmacists were actually handing out lethal combinations of drugs," says Dr. Flockhart. The study also sent shock waves through the medical community. But, as I discovered, the ripples haven't hit every every pharmacy.

One reason three of the pharmacists didn't quickly usher me out the door may have been that both prescriptions were written by the same doctor. They may have assumed the doctor knew what he or she was doing. But pharmacists are supposed to be the last line of defense.

Americans spend about $40 billion a year on prescription and over-the-counter medications. But we spend far more on mistakes. The annual toll of drug-related errors exceeds $76 billion. This includes failure of patients to follow instructions, but it also encompasses problems with dosage, drug choice, and harmful interactions.

The high numbers are no surprise to anyone who studies the issue. Many physicians have little understanding of medicine on a molecular level, says Dr. Flockhart. Only a minority of medical schools offers intensive traning in clinical pharmacology, he says.

Also, new medicines are continually being added to the market. So it's difficult, if not impossible, for doctors to keep abreast of every single drug.

"There are more and more good drugs coming out, but we're not using them well," says Dr. Flockhart. "There's no question in my mind about that."

While the Seldane-erythromycin alarm was first sounded in 1990, a recent study shows that not all doctors have gotten the word. Two to three percent of patients on Seldane also had prescriptions for other drugs, such as erythromycin, that could prove lethal if combined.

Hoescht Marion Roussel, the maker of Seldane, takes issue with this study, which appeared in the May 1, 1996, Journal of the American Medical Association. The study was funded by Schering-Plough Corporation, which makes a rival drug.

"Our own research shows only about one half of 1 percent of Seldane users have overlapping prescriptions for other drugs that can result in a dangerous interaction," says Hoescht spokesperson Diane Parks.

Seldane and erythromycin, it must be stressed, are by no means unique. Countless other drug combinations are just as dangerous--some even more so. But these two prescriptions are a frightening benchmark.

If they can be filled together, it's probably safe to assume less notorious, but equally risky, mixes are dispensed much more freely, says Joe Graedon, a leading authority on the problem and coauthor of The People's Guide to Deadly Drug Interactions (St. Martin's Press, 1995).

"Pharmacists who fill Seldane and erythromycin together need to have their heads examined," says Graedon. "But if you had picked two less obvious examples, my suspicion is the results would have been a lot more scary."

Graedon claims that adequate safeguards don't exist. For instance, the quaky of computer programs varies widely from pharmacy to pharmacy, he says. There's no standard system to alert druggists to a potentially fatal mistake.

The potential for deadly interactions grows exponentially. Each year, about 25 new drugs join the existing stock. This comes at a time when doctors are caught in the vise of managed care. Under pressure to see patients quickly, they may not thoroughly screen for interactions.

Pharmacists also are squeezed "They're asked to fill more prescriptions for less money," Graedon says. "But pharmacists don't have the time or the resources to do the job as they need to."

It doesn't take a genius to figure out that a high-pressure environment increases the propensity for mistakes. I called the one pharmacist who dispensed my drugs so freely to see if she remembered me. She did.

Apologetically, she explained that I had caught her during an unusually hectic moment. "It was one of those nights. What can I tell you?"

5 Ways to Protect Yourself

Avoiding dangerous drug interactions is largely up to you. That's because there's no reliable system to guard against swallowing a lethal combination of pills.

The best defense is to arm yourself with information. "Be aggressive consumers," urges David Flockhart, M.D., a clinical pharmacologist at Georgetown University.

Know exactly why you're taking each medication. Double-check the instructions and recommended dose. And read the following tips before filling your next prescription:

1. Remind your doctor of other drugs you're taking. This includes over-the-counter preparations and vitamins. Don't be lulled into complacency just because a product is sold without a prescription. Even aspirin can be dangerous when mixed with certain medications.

2. Make sure the prescription is legible. We hate to stereotype, but doctors have never been known for good penmanship. Make sure your prescriptions are easily read.

3. Choose a licensed pharmacist carefully and use the same one. Don't be fooled by the white coat. You may be speaking with a technician with no formal education in spotting deadly drug interactions. Insist on speaking to a licensed pharmacist who has time to spend with you, especially if you take multiple medications.

4. Educate yourself. Prescription labels and inserts contain potentially lifesaving information. Read them.

5. Report unusual symptoms. Any new complaint, such as headache, dizziness, or drowsiness, can be caused by medication. Never stop taking a drug, however, without your doctor's approval.

RELATED ARTICLE: Food and Drugs That Don't Mix

Did you know that a glass of grapefruit juice might kill you So could a large serving of broccoli. or even a piece of cheddar cheese.

All these foods can he lethal if mixed with the wrong medication.

Many interactions between drugs are well documented. But little is known about how food fits into the equation.

Here's a partial list of some foods and medicines that don't mix and shouldn't be taken together:

* Grapefruit juice and calcium channel blockers. A compound in grapefruit slows the rate the body metabolizes these drugs. in effect, making them much more potent. Don't drink grapefruit juice if you are taking Sandimmune. Seldane, or Hismanal.

* Broccoli and Coumadin (warfarin). This otherwise healthy vegetable can counteract the effect of Coumadin also widely prescribed blood thinner. People on Coumadin also should refuse large helpings of kale. brussels sprouts, and other foods rich in vitamin lit

* Cheddar cheese and MAO inhibitors. Aged cheese contains high levels of a chemical called tyramine. So do certain other products, such as pickled herring and fava beans. Patients taking antidepressants known as MAO inhibitors must avoid these foods.

* Licorice and Lanoxin. Don't overload on this sweet treat if you take Lanoxin, a heart medication. The combination could result in a serious heart disturbance.

COPYRIGHT 1997 Meredith Corporation
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