A report published online Monday in the Archives of Internal Medicine tested the potency of prescription medications that expired between 28 and 40 years ago — and found that nearly all of them were still fine to use.

A team of researchers affiliated with the University of California happened upon a pharmacy that had a stash of eight medications with expiration dates going back as far as the 1960s. All were unused, still in their original packaging. The scientists tested three capsules from each to see how much of their active ingredient remained present. The medications together accounted for 15 different active ingredients, including aspirin, amphetamine, codeine, phenobarbitol and acetaminophen.

One of those ingredients was excluded from testing because no standard for assessing its potency could be located. Of the remaining 14, all but two of the ingredients were found to be present in at least 90 percent of the amount listed on the label. (The paper explains that the FDA allows drug makers some leniency, requiring that medications contain between 90 percent and 110 percent of their active ingredient.) 

Three of the ingredients were found in amounts exceeding 110 percent of the labeled amount; the authors note that they may have been manufactured before the FDA’s regulations were in place.

Only aspirin and amphetamine were present in less than 90 percent of the label-listed amount.

The results are contrary to the commonly held notion that medications become suddenly useless once their expiration date arrives; the authors explain, “the expiration date is only an assurance that the labeled potency will last at least until that time.”

These findings could help point the way to huge health-care cost savings, the paper notes. If manufacturers could extend their expiration dates, people could replace their meds less frequently and save themselves, insurance companies, and the public health-care system huge sums. According to the paper, Americans spend more than $300 billion a year on prescription medications.

The paper’s publication comes weeks after the federal Drug Enforcement Administration’s annual National Take-Back Initiative (held this year Sept. 29), which encourages people to safely dispose of their expired prescription drugs. That event is aimed primarily at curbing prescription drug abuse.

Do you have expired drugs lurking in your medicine cabinet? Do you intend to use them, or are you inclined to just throw them out?