Many drugs remain potent long after their expiration dates
December 4, 2012, 1:56 am
Stability of Active Ingredients in Long-Expired Prescription Medications. Cantrell L et al. Arch Intern Med 2012 Nov 26;172:1685-1687.
The Food and Drug Administration does not require that manufacturers carry out studies to determine how long their medications retain potency. Usually, expiration dates are set — somewhat arbitrarily — at 12 to 60 months after production.The Shelf-Life Extension Program (SKEP) is a joint effort between the Department of Defense and the FDA with the the goal of minimizing drug replacement costs by determining if expiration dates on selected medications can be extended safely and effectively.
The authors obtained 8 medications (comprising 15 active ingredients) that had officially “expired” 28-40 years previously. They analyzed the pill contents to establish the amount of drug remaining.
Eleven ingredients — methalqualone, codeine, butalbital, caffeine, phenobarbital, pentobarbital, secobarbital, meprobamate, hydrocodone, chlorpheniramine, and acetaminophen — were present at > 90% of the listed amount. Two ingredients — aspirin and amphetamine — were present in quantities less than 90% lists. In the two products tested that contained aspirin, the drug had virtually disappeared. One drug — phenacetin — was present at > 90% listed in one preparation tested, but not in a second.
The authors conclude that their study “provides additional evidence that many prescription pharmaceuticals retain their full potency for decades beyond their manufacturer-ascribed expiration dates”. They point out that extending the expiration dates of appropriate medications may provide substantial cost-savings.