Extending the expiration dates of medications to better reflect the durability of their active ingredients could potentially yield significant savings on prescription drug costs.
Analysis of a cache of decades-old prescription medications discovered in a retail pharmacy has revealed that the potency of most of their ingredients was undiminished even though their expiration dates had passed years earlier. The results
of the analysis were published online on October 8, 2012, in Archives of Internal Medicine
The researchers worked with samples of 8 medications that had expired 28 to 40 years earlier and contained 15 different active ingredients in all. The researchers analyzed 3 tablets or capsules of each medication, and each sample was tested 3 times for each labeled active ingredient. (One active ingredient, homatropine, was not tested for as no analytical standard could be found for it.) The active ingredients tested for were: aspirin, amphetamine, phenacetin, methaqualone, codeine, butalbital, caffeine, phenobarbital, meprobamate, pentobarbital, secobarbital, hydrocodone, chlorpheniramine, and acetaminophen.
The results showed that 11 (79%) of the 14 drug compounds were always present in concentrations of at least 90% of the amount indicated on the drug label, which is generally recognized as the minimum acceptable potency. All samples of aspirin and amphetamine were present at less than 90% of the labeled content, and phenacetin was present at greater than 90% of the labeled amount in 1 medication, but less than 90% of the labeled amount in another medication. In addition, 3 compounds were present at greater than 110% of the labeled content, which is generally seen as the maximum acceptable potency.
The researchers note that aspirin is known to degrade over time, but that there is no published data regarding the durability of amphetamine. They note that the difference in measurements of phenacetin content may have been due to packaging and storage conditions. They add that some compounds present at greater than 110% of the amount listed on the label may have been from medications produced before 1963, when quality control measures were upgraded at the order of the FDA.
Expiration dates for drugs are generally set at 12 to 60 months after production, but the FDA does not require manufacturers to determine how long medications remain potent after their expiration date. Given that almost all the compounds in the current study retained full potency under conditions that may not have been ideal for 28 to 40 years, the researchers suggest that expiration dates for many medications could be extended. Doing so could potentially yield significant savings on prescription drug costs.
Further evidence of the possibility of extending expiration dates of prescription medications is provided by the Shelf-Life Extension Program (SLEP), a collaboration between the FDA and the Department of Defense that aims to reduce medication costs for the military. It has found that 88% of 122 different drugs stored under ideal conditions should have their expiration dates extended more than 1 year, with an average extension of 66 months, and a maximum extension of 278 months. The SLEP is extremely cost-effective; each dollar spent on it saves $13 to $94 in medication costs.