Menstuff® has compiled the following information on Perscription Drugs.
Bad Combinations: Drug interactions you and
your doctors need to worry about.
Drug Expiration Dates: Take Them Seriously
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Drug Expiration Dates: Take Them
Should you use the medicine, or not?
Some pharmaceutical experts are fond of pointing to a study done for the U.S. Army that found that many drugs were still usable nearly five years after the expiration date. But other experts say it isn't worth the risk and you should toss old drugs.
The Army study was presented at the 2002 U.S. Food and Drug Administration science forum. The review examined 96 different drugs, and included 1,122 lots in all, and found that 84 percent remained stable 57 months beyond the expiration date.
But even the researchers, in their report, said the additional stability period is "highly variable," depending on the drug.
"I would take expiration dates seriously," said Cynthia LaCivita, a pharmacist and director of clinical standards and quality for the American Society of Health-System Pharmacists, in Bethesda, Md.
"The longer you go beyond the expiration date, the more question there is about the activity of the drug," LaCivita added. "There are some other studies that show over time some of these drugs are degraded."
LaCivita recalled a recent study that found that liquid antibiotics, often prescribed for children's ear infections and meant to be stored no more than 14 days under refrigeration, began to lose some therapeutic value after the 14 days.
Manufacturers calculate expiration dates for drugs after testing the product to see how fast it degrades, she said.
LaCivita noted that the study conducted for the U.S. Army "looked at drugs in their original, unopened container. That is not usually how an individual would store a drug."
Most consumers don't store medicines in optimal conditions, making it even more crucial to pay attention to the expiration date, said Rachel Bongiorno, a pharmacist and director of the University of Maryland Drug Information Service. "To be on the safe side, I would never recommend anyone take medication past the expiration date."
If medicines, such as aspirin, look sticky or crumbled, it's a sure sign to toss them, said LaCivita.
"The biggest problem is, it won't be as effective," Bongiorno said.
But there are other reasons not to take old medicine -- like that back pain drug that worked years ago. "You may start a new medicine that may interact with the old one," Bongiorno said. "You may have another disease that could require a dose reduction" of the previous medicine.
LaCivita recommends people go through their medicine cabinet once a year and throw out expired drugs. She suspects that few people do this, based on the impromptu searches she carries out when she visits family members.
"I would have to say, based on my family members, I can always find medicines that are not just days but years out of date." And they're familiar with her cabinet-searching routine. "You would think they would listen to me," she said with a laugh.
If you use medicine before its expiration date, you can be sure
you're getting the medicine's best benefit, both experts said.
Bad Combinations: Drug interactions you and
your doctors need to worry about.
But theres also a great deal of uncertainty about how big a problem this really is. Theres no central clearinghouse of information on drug interactions or standardized reporting requirements. The FDA does have a reasonably good system for reporting adverse drug events, but interactions make up just a fraction of those.
Compounding the confusion is the absence of criteria and definitions. Harold DeMonaco, a drug therapy expert at Massachusetts General Hospital (MGH), says, Drug reactions are like beauty: They are in the eye of the beholder.
The ambiguity has caused problems. Hospitals have had to reprogram their computers because even the remotest possibility of an interaction was triggering an alert that doctors then had to override. They took lists of hundreds of possible interactions and boiled them down to a couple of dozen.
Some interactions dont occur because the medications are no longer used very much partly because they caused interactions. In other cases, a possible interaction has been identified but the risk may be largely theoretical. For example, an article published in Circulation in 2003 suggested that Lipitor (atorvastatin), the popular cholesterol-lowering statin, may cancel out the effects of Plavix (clopidogrel), a drug that prevents blood clotting. But the Lipitor-Plavix problem is a formulated but untested hypothesis, according to an article written by Robert Hallisey, a pharmacist at MGH. Hallisey noted that researchers havent seen the interaction in the numerous studies of Plavix.
Dr. David Bates, a Harvard expert on adverse drug events, was one of the authors of a study published in the Journal of the American Medical Association in 2003 that helps put drug interactions in perspective. Bates and his colleagues examined the medical records of about 28,000 Medicare enrollees who were 65 or over. Of the 421 preventable adverse drug events, 56 were drug interactions, a sizable (13%) fraction. But that was considerably fewer than the 89 (21%) adverse events caused by errors in patient adherence people taking the wrong dose, refusing to take a drug, and so on.
Six important drug interactions
We asked Dr. Bates, DeMonaco, and other Harvard experts to help us create a short list of important drug interactions. We picked six. Obviously, this leaves many interactions unmentioned but it highlights some of the important problems and the reasons they occur.
Warfarin (Coumadin) with antibiotics. Warfarin is a blood thinner that people with atrial fibrillation and other heart problems take to prevent the formation of blood clots. Many drugs, including warfarin, have a tendency to stick to albumin, a protein in the watery part of the blood. If another drug successfully competes with warfarin for that binding site on albumin, then the concentration of free, and thus active, warfarin soars and with it the risk of serious bleeding. A common bad combination is warfarin and sulfa antibiotics such as cotrimoxazole (Bactrim, Septra, other brands) particularly in nursing homes, where residents with atrial fibrillation are also frequently prescribed antibiotics for urinary tract infections and pneumonia. The warfarin dose should be lowered and the bloods clotting capacity closely monitored.
ACE inhibitors with NSAIDs. ACE inhibitors are used to treat hypertension and heart failure. The NSAIDs include aspirin, ibuprofen (Advil, Motrin, other brands), naproxen (Aleve), and a COX-2 inhibitor like Celebrex. In some patients, NSAIDs make ACE inhibitors less effective in lowering blood pressure. If youre taking an ACE inhibitor, talk to your physician about which pain reliever to take. The occasional ibuprofen is not going to cause harm, but the long-term use of both classes of drugs could.
Digoxin with azithromycin, clarithromycin, or erythromycin. Digoxin (pronounced di-JOCKS-in) is prescribed to strengthen the heartbeat of people with heart failure. The -mycin drugs are antibiotics. Digoxin is metabolized by bacteria in the gut, so not all of it gets absorbed. But these antibiotics kill many of those bacteria, so the absorption of digoxin increases, which may cause an irregular heartbeat.
Potassium supplements with potassium-sparing diuretics. When diuretics pull water out of the bloodstream, they pull salt and potassium along with it. Low salt levels arent usually a problem, but low potassium levels can be, so potassium supplements are sometimes prescribed. But if you have heart failure or your blood pressure isnt controlled by a diuretic, doctors will sometimes prescribe a potassium-sparing version (Aldactone, Dyrenium, other brands) in addition to or in place of the regular diuretic (see Beware of low potassium levels from diuretics, Harvard Health Letter, April 2004). If you keep taking the potassium supplements, then youll end up with too much potassium in your blood, and that excess can cause serious problems, including cardiac arrest. Combining ACE inhibitors with potassium-sparing diuretics sometimes also leads to high potassium concentrations.
The -azole antifungals and statins. The -azole antifungals, which include fluconazole, itraconazole, and ketoconazole, are oral drugs used to combat fungal infections in the vagina, lungs, and elsewhere. Like many other drugs, including many of the statins, the -azole drugs are metabolized in the liver by a group of enzymes called the P450 enzymes. When an -azole antifungal and a statin share the P450 enzymes, the concentration of the statin can shoot way up, and high levels can cause muscle damage.
The erectile dysfunction drugs and nitrates. Viagra, Levitra, and
Cialis all interact with nitrate-based drugs such as nitroglycerin to
produce a sudden drop in blood pressure. The interaction has been
well publicized and is frequently mentioned in the many ads for these
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