Do expiration dates make a difference?

Fewer than a third of adults clean out their medicine cabinet annually-compared with 49% who update their wardrobe to reflect the current season.

A Harris poll conducted in June found that 61% of Americans regularly check expiration dates on OTC medications, but a new survey indicates that nearly half of American adults have used expired medications.

"It's important for people to realize that ignoring the expiration information on their medications may post potentially harmful risks to their health," cautioned Janet Engle, Pharm.D., associate dean and clinical professor of pharmacy practice at the University of Illinois at Chicago College of Pharmacy. The Food & Drug Administration also advises consumers to discard all medications, prescription as well as OTC, at the expiration date.

The shelf-life data that are made public can be confusing. For the Department of Defense, the Food & Drug Administration routinely recertifies shelf-life extensions years beyond the original expiration date.

"Drug manufacturers generally give products a two- to five-year expiration date," said Robbe Lyon, Ph.D., division director, division of product quality research, FDA Center for Drug Evaluation & Research. "The real shelf life of a drug is not public knowledge. That is why the SLEP program exists."

The Shelf Life Extension Program (SLEP) began with an Air Force pilot project in 1985. In 1986, the FDA began testing drugs for all four of the armed services. The program covers several dozen products that have no civilian market or which the Defense Department buys in such large batches that vendors will not accept returns upon expiration. Drugs that retain at least 90% of their original potency are relabeled with an extended expiration date. The extended date allows the military to avoid destroying and replacing drugs that still meet the original stability and potency standards. Of the drug products tested under SLEP, 86% get an extended expiration date, Lyon said. Tests are conducted by lot, and any extension of shelf life is for the tested lot only.

According to Defense Department documents, the long-time winner is a pralidoxime autoinjector, originally labeled for five years and found to be potent for 18 years. Other long-life products include sodium thiosulfate (16 years), atropine sulfate (15 years), ciprofloxacin (13 years), and atropine autoinjector (10 years). Other products, Lyon noted, "fail potency testing rather soon after the original expiration. Epinephrine and mefloquine (Larium, Roche) give us a lot of problems."

But that does not mean consumers should buy a bottle of Cipro (ciprofloxacin, Bayer) and keep it for a dozen years, Lyon said. The military stockpiles drugs in the original packaging under controlled temperature and humidity conditions. Even under optimal storage, SLEP finds dramatic variations in shelf life between lots. That means SLEP results cannot be extended to hospital or retail pharmacy stocks.

Pharmacists and consumers are left to rely on expiration dates, beyond-use dates, and use-by dates. The three are, however, a confusing, sometimes conflicting, set of terms that mean different things to different people.

The expiration date printed on a drug package is set by the drug manufacturer, explained Claudia Okeke, Ph.D., an associate director at the U.S. Pharmacopeia. The maker certifies that the product will maintain at least 90% of its original potency until the expiration date. The certification requires the product to be stored according to label directions with the original packaging intact and unopened.

The expiration date on an individual prescription is set by the pharmacist. Meds dispensed in the original packaging retain the manufacturer's expiration date, but when a pharmacist compounds or repackages into consumer containers, the script gets a new date. It is not an expiration date, but a beyond-use date (BUD) or use-by date.

The BUD on compounded products is based on the ingredients and product risk levels as defined by USP. The USP generally requires a one-year (or shorter) use-by date on drugs that have been repacked for dispensing.