Drug expiry dates – are they ever too old?

DRUG BUST by Alan Cassels

• The people’s briefing note on prescription drugs

A little while ago I was talking to a physiotherapist who asked me if I was taking anything for some joint pain I was having. I pulled out a bottle of acetaminophen – also known as Tylenol – and she took the bottle from me.

“Alan,” she asked, with a bemused smile, “did you know these expired in May 2001?”

No, I didn’t. Shows how observant I am. Perhaps a 14-year-old bottle of Tylenol gives you some sense how infrequently I take the stuff.

It’s not the first time I’ve thought about the meaningfulness of expiration dates on our medications. Frequently, I wonder, “Does it make any difference taking drugs that are far past their expiry? And is it harmful to be swallowing medications that were made in the last millennium?”

Quick answers: probably not and probably no.

Health Canada requires drug makers to put expiry dates on their drugs, an acceptable precaution given that a drug’s ‘active’ ingredient may lose its potency over time. For some conditions, a drug’s potency is vital. The expiry date is the date by which a drug maintains its “labelled potency, purity and physical characteristics,” but it’s also “the minimum after which the manufacturer recommends that the drug not be used.” No one gives a maximum date.

From a merchant’s perspective, a short expiration date drives return customers. If your clients only use your product intermittently, expiry dates get them back to purchase more of the product. You often hear pharmacists and regulators hectoring about medication expiry dates, warning you in grave tones that you could be taking dangerous chances by swallowing expired drugs. Hmm, how true is that?

Phil Emberley at the Canadian Pharmacists Association in Ottawa answered some of my questions on this issue. His association enforces “standards of practice” for pharmacists and one of those “standards” is that pharmacies are not allowed to sell expired drugs. While such policy is there to protect the sanctity of the drug supply, Emberley admits the science around expiry dates is weak. Some drugs definitely lose their potency or stability over time – “drugs like insulin or epinephrine,” he says. But I wondered about expiry date economics. If a manufacturer’s expiry dates are ridiculously short, is this not a handy way to ensure patients are maximally gouged?

“I won’t wade into that one,” says Emberley. Understandably, pharmacists lean to the side of caution because they don’t know how well patients store their medications – where exposure to heat and humidity could degrade the drug. If a drug is stored properly, in the container it came in and away from light, heat and humidity, do you need to worry about its safety if it sails past the “best before” date?

I managed to track down the one guy who would know. Lee Cantrell is the director of the California Poison Control Centre based in San Francisco and is one of only a handful of researchers in the world who have studied the potency issue around expired drugs. And when I say “expired,” I mean “very expired.” The drugs he examined for a 2012 study in the Journal of the American Medical Association were 28 to 40 years beyond their expiry date.

He told me someone offered him access to a stash of unopened medications “squirreled in the back in a community pharmacy. As a scientist, I said, wow, this is a great opportunity to look at these medications to see if they could remain viable decades after they were produced.” He said he was never comfortable with the “relatively arbitrary process” used to dream up drug expiration dates and relished looking into the issue.

Mostly, it was the safety question that piqued his interest. He said he’d often get calls at the Poison Control Centre from people who discovered they’d accidentally swallowed an expired medication. “They’d freak out, saying ‘Oh my God, I just took an expired med, am I going to die?’”

His study looked closely at 14 expired drugs, 12 of which were “present in concentrations at least 90 percent of the labelled amounts.” This is considered the minimum “acceptable potency.” Basically, these decades-old drugs were as potent as the day they were manufactured; in fact, he found that those 12 medications “retained full potency for at least 336 months, and eight of these for at least 480 months.”

Lee Cantrell clearly doesn’t want people to think his research was an invitation to take expired medication. “That was not my conclusion at all. We didn’t study efficacy or safety, only potency,” he says.

Cantrell’s study was unique but tiny compared to what the US military did when it launched its Shelf Life Extension Program (SLEP) in 1986. Because the US government stores one of the biggest stockpiles of medications, it needs to know how potent those drugs are after their expiry dates. SLEP examined 122 different drugs past their expiry dates and found that almost 90% of them could easily have had their expiry date extended by a year. In fact, on average, they felt they could safely extend the expiry dates of those drugs by more than five years.

But there are caveats around this kind of research. The drugs in both Cantrell’s study and SLEP were stored properly, unopened, with both temperature and humidity controlled. And these were tablets and capsules, which remain stable much longer than drugs in suspension liquids.

The occasional pharmaceutical consumer might look at this and ask, “How much do those drug expiration dates really matter?” When a batch of yogurt or leftover pasta at the back of the fridge goes bad, your nose tells you, but with drugs, we have to take the manufacturer’s word for it.

One thing is clear: there is very little evidence that people can be harmed by taking expired medications. Anecdotes, however, are powerful. Every pharmacist in the world has had drummed into their heads a case study of expired tetracycline causing Fanconi syndrome in 1963. It should give one solace that, if citing a 52-year-old case study of an expired drug is the best they can do to scare you about the practice, it’s unlikely expired medications pose huge safety concerns.

For me, the lack of documented harms tells me that when (and if) drugs degrade over time, they may become useless, but they probably won’t become toxic. Today, drug companies are required to test their drugs for stability and will state on the label if the product, once expired, is risky.

Is it possible the biggest harm from drug expiry dates is not health harm, but economic and environmental waste? When people are warned, time and time again, to discard their drugs once they’ve become expired, are they filling landfills to pollute the environment and wasting their (and our) money? Ditching good, but out-of-date, drugs probably costs all of us hundreds of millions of dollars every year, but what’s the solution? I’m not suggesting a revolt at the pharmacy; what I am suggesting is better independent research on expiry dates to ensure that Canadian consumers can have drugs with reasonable expiry dates informed by science, not marketing.

This might have resonance at the national level. Back in 2004 or so, public health officials in Canada started stockpiling huge batches of antiviral drugs Tamiflu (oseltamivir) and Relenza (zanamivir) in case of an influenza pandemic. Said pandemic didn’t materialize. The drugs were good for probably five years from the date of purchase. So, in my estimation, Canada is sitting on two federal stockpiles holding about $150 million worth of antivirals and the provinces also hold hundreds of millions of dollars worth. BC’s alone is worth about $35 million.

I tried hard, but no one at Health Canada could tell me when and if these drugs were expiring. Let me hazard an educated guess: they are almost all expired and by next year, 2016, the entire stockpile will be expired.

Does Canada throw away hundreds of millions of dollars worth of expired drugs or spend a bit of money to find out if they might be effective? We’ve got a new government that might be interested in this kind of public-interest research. Stay tuned on this one.

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Alan Cassels is a pharmaceutical policy researcher, an occasional swallower of expired acetaminophen and the author of a new book, The Cochrane Collaboration: Medicine’s Best Kept Secret. @AKECassels. You can read more of his writings at www.alancassels.com or follow him on twitter @akecassels