Prescription Drugs: Still Potent Years After Expiration Date

Lawrence LeBlond for – Your Universe Online

Every year millions of people are tossing out drugs that have reached or passed their expiration dates; many could be doing so because they believe such drugs are not as potent as they once were. However, a new analysis of eight prescription drugs that have well-surpassed their discard date, some by as much as 40 years, has found that these drugs are just as potent as the day they were manufactured.

Just as most consumers are curious as to whether these outdated drugs are safe, so were researchers from the California Poison Control System, UC San Francisco and UC Irvine. Armed with an array of eight drugs between 28 and 40 years past their prime, the researchers tested their effectiveness levels to see if they had in fact gone bad.

The drugs tested came from pharmacy shelves, many sitting around collecting dust for decades, and had remained sealed in their original containers.

The researchers focused their studies on 15 active ingredients found in the drugs, including acetaminophen, codeine, caffeine,  hydrocodone, aspirin, amphetamine and others.

The researchers couldn´t find a standard test for one ingredient, homatropine, so they dropped that one from their analysis.

To test their potency levels, the researchers dissolved the drugs and subjected them to chemical analysis using a mass spectrometer, which revealed how much of the active ingredients remained in the pills. Out of the 14 tested ingredients, 12 were still at high enough concentrations (90 percent) to qualify as having “acceptable potency.”

The only two active ingredients that lost any significant amount of potency were aspirin and amphetamine. In the remaining 12, the potency levels fall within the range deemed acceptable by the Food and Drug Administration, which allows “reasonable variation” in the strength of prescription drugs, requiring that they contain generally between 90 and 110 percent of the stated active ingredient.

In most of these drugs, expiration dates are labeled to between one and five years after manufacture. However, the FDA does not mandate that drug companies must test how long their active ingredients will last and most expiration dates are set randomly and without any logic, said the researchers.

“All [the expiration date] means from the manufacturers’ standpoint is that they’re willing to guarantee the potency and efficacy for the drug for that long“¦It has nothing to do with the actual shelf life,” noted lead author Lee Cantrell, a professor of clinical pharmacy at the University of California, San Francisco.

The study results do not indicate the effectiveness of these eight drugs tested, but Cantrell said there is no reason to think otherwise. It is likely that many people are throwing out their outdated pills prematurely. And this could have important implications for drug shortages and health care costs.

“We’re spending billions and billions on medications and medication turnover,” Cantrell said. “If a drug has expired, you’ve got to throw it away, it goes into a landfill, and you have to get a new prescription. This could potentially have a significant impact on cost.”

And although there could be complications from taking medications with less potency, expired drugs are generally safe. As far as the researchers know, there is only one example of a drug becoming toxic after reaching its expiration date, and that was an isolated incident.

Surprisingly, three ingredients tested were found in amounts greater than 110 percent of label strength. The researchers noted that it is likely the drugs containing these ingredients were manufactured before quality-control regulations were introduced by the FDA in 1963.

The government´s Shelf-Life Extension Program allows drugs to be retained for up to 23 years (278 months) after they expire if tests show they remain potent. But Cantrell and colleagues found that some of the ingredients tested remained good for up to 40 years (480 months)–and who knows, they could even last longer.

Perhaps the most important implication of the study “involves the potential cost savings resulting from lengthier product expiration dating,” said the researchers. “Given that Americans currently spend more than $300 billion annually on prescription medications, extending drug expiration dates could yield enormous health care expenditure savings.”

However, Cantrell cautioned that people should not go digging through their trash to retrieve their discarded drugs just yet.

Some of the drugs tested in the latest analysis are no longer widely used, and it is not clear if these results carry over to other newer types of drugs on the market, or for similar drugs stored in different conditions, Mohammed Nutan, an associate professor of pharmaceutical sciences at the Texas A&M Health Science Center, in Kingsville, told´s Amanda Gardner, as reported by CNN.

The drugs in the study were unopened and still in their original containers. Those that have been opened and/or stored in inappropriate conditions may pose a significant health risk, Nutan warned. Humidity, temperature and light exposure can affect how long a drug remains potent, and perhaps its toxicity.

Despite this, Cantrell said his team´s findings indicate that expiration dates on at least some drugs could be safely extended. “Perhaps expiration dating of medications needs to be revisited,” he added.

The researchers reported their analysis findings in the online edition of the Archives of Internal Medicine.