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The question

I have severe food allergies and I’m at risk of suffering anaphylaxis – making it difficult, maybe even impossible, for me to breathe. I always carry an EpiPen auto-injector just in case I need emergency medicine. Now I see in the news that these life-saving products are in short supply. How long will an EpiPen still work after it’s past its expiry date?

The answer

The medication in an EpiPen doesn’t suddenly become useless once the expiry date on the label has been reached. But how long it remains effective is a matter of some debate and conjecture. That uncertainty also applies to other prescription and over-the-counter drugs.

Before reviewing the evidence, though, a bit of background is in order. Pfizer Canada Inc. is the sole Canadian supplier of an auto-injector (known by the brand name EpiPen) that enables patients to quickly give themselves a shot of epinephrine, which acts as an antidote to anaphylaxis – a potentially deadly allergic reaction. The company says a “manufacturing issue” has led to delays in shipping new supplies of the adult-dose EpiPen to pharmacies, some of which may run out of stock before the end of August.

This supply problem prompted Health Canada to take the unusual step of advising patients to use an expired EpiPen – if that’s all they have – and call 911 to get to a hospital emergency department.

In general, drug manufacturers are required to provide Health Canada with evidence their products retain potency for at least a certain period of time. “Expiration dates indicate the time at which the full potency and safety of the medication may begin to diminish,” says Christina Antoniou, a spokesperson for Pfizer Canada Inc.

Typically, the expiration dates for most drugs are set at two or three years from the time of manufacture. EpiPens have an even shorter shelf life – about 18 months. But there’s been very little research done on how quickly – or slowly – drugs break down after the expiry date. Several intriguing studies suggest that certain medications, including the epinephrine in an EpiPen, might be relatively stable and still effective for a surprisingly long time.

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Typically, the expiration dates for most drugs are set at two or three years from the time of manufacture. EpiPens have an even shorter shelf life – about 18 months. But there’s been very little research done on how quickly – or slowly – drugs break down after the expiry date.Jim Bourg

“We found that the vast majority of expired EpiPens had at least what might be considered a therapeutic dose for up to four years after the expiration date,” says Lee Cantrell, director of the San Diego division of the California Poison Control System.

Cantrell and his research colleagues decided to do a study of expired EpiPens, after the manufacturer dramatically increased the price in the United States. He noted that many American patients had been asking their health-care providers if they could use expired EpiPens because they couldn’t afford to replace them. (EpiPens come in double packages in the United States and can cost over US$600. In Canada, they’re sold as singles with a price of about $100.)

The researchers collected 40 expired EpiPens from patients and physicians at a community health clinic. The samples ranged from one month to 50 months past the expiry date. “Although we observed declining concentrations of epinephrine over time, we expect the dose available 50 months after the expiration date would still provide a beneficial pharmacologic response,” according to the researchers whose results were published in 2017 in the Annals of Internal Medicine.

Cantrell led another study that suggests expiry dates significantly understate the actual shelf life of many other medications. Through a colleague, he gained access to a box of old medications that had been stowed away in a family-run pharmacy. Some of the drugs were still sealed in their original containers and exceeded their expiry dates by 28 to 40 years. An analysis revealed 12 of 14 drug compounds were present in concentrations of at least 90 per cent of their labelled amounts, which is generally considered an effective dose.

Despite his own study findings, Cantrell does not recommend the use of expired drugs. “You can’t say in broad strokes that all medications are good well past their expiry dates.” What’s needed is more research, says Cantrell, but “it’s not in the financial interest of any pharmaceutical manufacturer to do those studies.” After all, they make money whenever an expired drug is discarded and a new one purchased. “If we had additional data, we could potentially save billions in health-care dollars,” he says.

In fact, the U.S. government – which stockpiles medications in the event of a national emergency – took action long ago to reap some of those savings. In 1986, the U.S. military, along with the Food and Drug Administration, established the Shelf Life Extension Program. Samples of drugs stored by government agencies are routinely analyzed, and if they pass a potency test, their expiry date is extended.

Unfortunately, the U.S. government doesn’t routinely share those test results with anyone else. So, pharmacists and health-care institutions are professionally obligated to adhere to the existing expiry dates.

“The bottom line is the safety and health of the patient,” says Karen Lam, a pharmacist at Sunnybrook Health Sciences Centre in Toronto. “In emergency situations like the current EpiPen shortage, we do suggest patients use their expired EpiPen because some medication is better than none, especially in life-saving situations,” she explains.

Paul Taylor is a patient navigation adviser at Sunnybrook Health Sciences Centre. He is a former health editor of The Globe and Mail. Find him on Twitter @epaultaylor and online at Sunnybrook’s Your Health Matters.