The military was sitting on a $1 billion stockpile of drugs and facing the daunting process of destroying and replacing its supply every 2 to 3 years, so it began a testing program to see if it could extend the life of its inventory. The testing, conducted by the US Food and Drug Administration (FDA), ultimately covered more than 100 drugs, prescription and over-the-counter. The results showed that about 90% of them were safe and effective as far as 15 years past their original expiration date.As the author of the article says, this is one of those things where medicine manufacturers don't have any incentive to tell us that their drugs are good for a longer period of time. If I don't have any aspirin and I'm hung over, I'm going to buy some regardless of what expiration date is printed on the package. Short expirations don't keep me from buying the product. But if I have some expired aspirin, I might throw it away one afternoon and plan to buy a new bottle. Knowing this, manufacturers are going to err on the side of short expiration dates.
So who does the studies to figure out the truth about this? Well, the military, since they have a $1 billion drug stockpile that they don't want to throw away. You have to be really big -- like, Army big -- before funding a study like this is in your own interest. Otherwise, it's a classic collective action problem. All us consumers would be happy to pay a dime each for a big study on the issue, but there's no way for us to coordinate our action, especially as free riders could find ways to get the information without paying in. There's probably tons more information like this out there that could save us money or improve our health, but which we don't know because no one entity finds it in their interest to pay for the relevant study. Until then, drugmakers and medical device manufacturers will continue to take our money with marketing gimmicks (they spend far more on marketing than R&D) and give us poor value.
This will continue until there's some Army-like health care provider large enough that it's worth its while to pay for expensive but comprehensive and rigorous studies. And that's why we love Comparative Effectiveness Research, and look forward to the day when medical innovation is saved by a big government health care plan.
[Update: Medscape is behind a paywall. For some reason I can get to the article through Google, but not via the link above. Minus the approving comments from a UChicago psychopharmacologist, the link to the expired medicine article is here.]