http://www.health.harvard.edu/fhg/u...date1103a.shtml
It turns out that the expiration date on a drug does stand for something, but probably not what you think it does. Since a law was passed in 1979, drug manufacturers are required to stamp an expiration date on their products. This is the date at which the manufacturer can still guarantee the full potency and safety of the drug.
Most of what is known about drug expiration dates comes from a study conducted by the Food and Drug Administration at the request of the military. With a large and expensive stockpile of drugs, the military faced tossing out and replacing its drugs every few years.
What they found from the study is 90% of more than 100 drugs, both prescription and over-the-counter, were perfectly good to use even 15 years after the expiration date.
So the expiration date doesn't really indicate a point at which the medication is no longer effective or has become unsafe to use. Medical authorities state expired drugs are safe to take, even those that expired years ago. A rare exception to this may be tetracycline, but the report on this is controversial among researchers. It's true the effectiveness of a drug may decrease over time, but much of the original potency still remains even a decade after the expiration date.
Excluding nitroglycerin, insulin, and liquid antibiotics, most medications are as long-lasting as the ones tested by the military. Placing a medication in a cool place, such as a refrigerator, will help a drug remain potent for many years.
Is the expiration date a marketing ploy by drug manufacturers, to keep you restocking your medicine cabinet and their pockets regularly? You can look at it that way. Or you can also look at it this way: The expiration dates are very conservative to ensure you get everything you paid for. And, really, if a drug manufacturer had to do expiration-date testing for longer periods it would slow their ability to bring you new and improved formulations.
The next time you face the drug expiration date dilemma, consider what you've learned here. If the expiration date passed a few years ago and it's important that your drug is absolutely 100% effective, you might want to consider buying a new bottle. And if you have any questions about the safety or effectiveness of any drug, ask your pharmacist. He or she is a great resource when it comes to getting more information about your medications.
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Expiration Dates
"Expired medication" also represents a potentially large source of supply of medicine for a recycling program. As things stand now, expiration dates get a lot of emphasis. For instance, there is a campaign, cosponsored by some drug retailers, that urges people to discard tablets or capsules when they reach the date on the label.[23] It turns out that the date on the label, however, is often much earlier than the official expiration date. Pharmacists are required to put a "beyond-use" date on prescriptions, which is either the manufacturer's expiration date or 1 year from the date the drug is dispensed, whichever is earlier. The rationale is that containers into which dosage forms are repackaged may not have the integrity of the original package.[24]
However, not only the beyond-use date, but the official drug expiration date itself is usually determined conservatively, and very expensive medication is being wasted. Data from the Department of Defense/US Food and Drug Administration (FDA) Shelf Life Extension Program, which tests the stability of drug products past their expiration date, showed 84% of 1122 lots of 96 different drug products stored in military facilities in their unopened original container would be expected to remain stable for an average of 57 months after their original expiration date.[25] Some US Army studies on Valium, for example, show that the drug is very stable and completely safe and effective for up to 8 years after manufacture. Tablets of ciprofloxacin, an expensive antibiotic, were found completely safe and effective when tested 9.5 years after the expiration date. A recent issue of The Medical Letter[26] quoted not only the above study but others showing expensive medications like amantadine (Symmetrel) and rimantadine (Flumadine) remained stable after storage for 25 years under ambient conditions and retained full antiviral activity after boiling and holding at 65-85° C for several days. Theophylline, in tablet form, shows 90% stability even after 30 years beyond the expiration date.[27] Such stability is not reflected in the manufacturer or pharmacy dating about when tablets or capsules must be discarded. In general, although published data are not available for all medicines, The
Medical Letter consultants believe that most drugs stored under reasonable conditions retain at least 70% to 80% of their potency for at least 1 to 2 years after the expiration date, even after the container has been opened (nb: current US Pharmacopoeia [USP] standard is generally 90% potency).[28] With new individual pill packaging techniques, it is highly likely that USP acceptable potency would be the norm over that same time period.
The only report of human toxicity that may have been caused by chemical or physical degradation of a pharmaceutical product is a disputed article (published in 1963) alleging renal tubular damage associated with use of degraded tetracycline.[29,30] The lack of other reports of toxicity from expired medication is reassuring, but the topic of out-of-date medication toxicity is not a well-researched issue.
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