prescription drugs medicine chest drug expiration
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Have you ever looked at the label of an old medicine bottle before you deigned to take the pill? Of course, you have. You were looking for the expiration date. And how many of you threw away the bottle of aspirin because it exceeded its allotted lifetime and expired? I am sure the majority of us have done it. Now, I am not a conspiracy theorist, but having had the privilege of an inside look at the working of drug companies, I can’t escape the feeling that it’s time to critically examine the process behind those menacing word of “Warning: Do not take after such and such a date.”


How is the drug expiration date determined?

When a drug is in the process of development, the company is obliged to conduct stability studies. From Day 1, samples of the drug are kept at different temperatures (4-6°C, room temperature, 37°C) to simulate conditions in which the drug may be stored and, sometimes, other environmental factors, like dark/light, relative humidity, and so forth. These stability studies continue throughout the development of the drug. Let’s take a typical development period of 12 years. At the end of this period, the company submits a New Drug Application (NDA) to the FDA. And among the reams of data on what is known about the drug, there is one critical page: THE LABEL.

What you put in the label has to hew closely to what the data show—up to the date of submission. Everybody is involved in crafting the content of the label: the chemists who can attest to its structure, purity, and stability; the biochemists who are supposed to know about the drug’s metabolism and breakdown products in the body and in storage; the toxicologists who tested for any adverse effects on animals and humans; the clinicians who conducted the clinical trial and can attest to its efficacy.

But wait, that’s not the whole story. The marketing people weigh in as well. What does the marketing department have to do with the label? Everything that is important to the bottom line, that’s what. Use the wrong language in the warnings section and physicians and patients will avoid you like the plague. Push the envelope a bit in your efficacy claims, and you could gain market share worth billions of dollars over many years. Can one blame them for trying? Of course, the FDA stands guard against such abuses, but as we all know, even they are not immune to the power of lobbying and political pressure.

So what about the stability data? If the drug had a 12-year development period, the company has only 12 years of data on stability. But that’s the maximum. The FDA encourages the company to take a conservative stance, and the company happily obliges. So, they take a healthy “discount” to the stability period of the 12 years, which the data shows, to say 6 years. The company can claim they are placing patients’ interest as their top concern. It will also help in product liability lawsuits. And, it will induce you to throw away a perfectly good drug and buy a replacement. And this translates into mucho moolah.


The drugs do break down, but slowly

Now, before the chemists and pharmacologists among you get your dander up, let me say that there is always a slow process of breakdown of any chemical, including drugs. But the emphasis is on “slow”. If it weren’t slow, it wouldn’t pass muster with the FDA. Now, let’s say that in 12 years, the company showed a 10% loss of efficacy. That would translate to taking 360 mg of 12-year old aspirin instead of 400mg of newly synthesized aspirin.

But wait! If you took that aspirin at 6 years, still within the approved period, your effective dose would be only 380mg. Now the important question is “Has anybody bothered to measure the differences in analgesic and anti-inflammatory activity between 360mg, 380mg, and 400mg?” To my knowledge, nobody. Academic scientists wouldn’t because the difference would be so minuscule as to be meaningless. Company scientists, of course, wouldn’t, because their company doesn’t want to know—it may cause a drop in sales.


How much could we save?

The problem is that the consumer doesn’t have a way of knowing what is the real expiration date. And, this is not a problem limited to consumers losing money and companies making it; it is a national problem, as a quick look at what the nation spends on medicating itself would reveal. Medicare Part D, which pays a large portion a patient’s drug bill, plays a major role in the precarious financial situation we are finding ourselves in. How much can be saved by simply keeping an effective drug a bit longer? The arithmetic is quite simple: A 10% reduction in drug consumption related to extending expiration dates would translate to a 10% reduction in the national expenditure on medicines.

When we face a complex problem, like healthcare, we instinctively reach for a complex solution. But sometimes, solutions can be simple and hiding in plain view. All we need is to “get in the weeds”, test our assumptions, examine the data behind the assertions, and separate fact from fiction.

Why don’t we do it?

This post was originally published on 10/9/2011. It was reviewed and updated by the author on 06/06/2017.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Thanks for the blog Dov. I talked with a bio-chemist about this recently. His group determined 80% of the active ingredients were still good and useful after 5 years. Corporations will do whatever they can to increase the bottom line.

  2. Great topic. I have long suspected that the drug expiration date was the date in which the drug might lose potency, rather than the common perception–the date at which the drug might somehow become dangerous. This advances my understanding greatly. Nice work and thanks.

  3. The Air Force did a study on this and showed that most expiration dates were bogus, that drugs not exposed to extreme heat kept their stabiltiy far longer than the (shrinking) potency periods claimed on the labels. As a result — as you say — a lot of moeny was being wasted. The drug companies admitted as much when faced with this evidence, claiming instead that the LABEL could expire and needed to be kept up to date.

    Most expiration dates are a year these days. Perhaps someone from the drug companies should explain how the length of time it takes the earth to get around the sun affects drug potency.

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