Throw out expired meds? Maybe not

Q. I hope you can resolve a problem that worries me. My husband refuses to throw out pills that are past their expiration dates. I never keep foods longer than I should, so I hope you'll convince him to clean out the medicine chest the way I take care of the fridge and pantry.

A. Your question poses a challenge to both diplomacy and science. Although there's relatively little scientific data about outdated medication, it seems diplomatic and accurate to say that you're both likely to be right. Keep policing your foods, but cut your husband a little slack about his pills.

Expiration dates for medicines are established by law, not science. In general, drug companies give their products an expiration date two to three years from the date they're manufactured. But when your pharmacist opens the bulk container and repackages the medications for your use, he labels your bottle with an expiration date that's usually one year from the day your prescription is filled.

There's no evidence that outdated medications are toxic or harmful; the only example in medical history occurred in the 1960s, and the drug in question (tetracycline) has been reformulated.

Although toxicity is not a concern, loss of potency is a possible worry. But when the Department of Defense/U.S. Food and Drug Administration Shelf Life Extension Program tested 1,122 lots of 96 different drugs stored in their original containers in military facilities, they found that 84 percent would be expected to remain stable for an average of 57 months beyond their expiration dates. And a study of the anti-influenza drugs amantadine (Symmetrel) and rimantadine (Flumadine) found that these drugs remained fully active after 25 years of storage.

It's reassuring news, but there are exceptions. The most notable is nitroglycerin, which should be replaced every six months. The epinephrine in EpiPens loses its potency when it has passed its expiration date. In addition, liquid drugs, including oral suspensions and solutions and injectable products, are less stable than tablets or powders.

Remember that these favorable results apply to medications that have been stored properly. Always keep your drugs in a cool, dry place in their original containers. Never take a drug that looks, smells, or tastes funny. And even if you keep using a medication a bit beyond its expiration date, you should discard those you no longer need - a tidy medicine chest will reduce the risk of errors, just as a tidy refrigerator will reduce the problem of mystery leftovers.

A respected authority, The Medical Letter on Drugs and Therapeutics, concluded that "many drugs stored under reasonable conditions retain 90 percent of their potency for at least five years after the expiration date on the label, and sometimes much longer."