The COVID-19 pandemic

[danbrotherston]

In fact, a significant amount of drugs in existence are fine well past their expiration date.

I would assume that the expiry date is the date to which the drug is known to be good, just like the approved population and dosage is the population and dosage for which it is known to be safe and effective.

So just as drugs will often be safe in populations which haven’t been studied and in doses which haven’t been studied, so to will they continue to be effective a certain amount of time past their due date.

This is inevitable given the nature of drug research: to develop a drug which can be used. That doesn’t require fully researching just exactly how long it lasts, only establishing that it lasts long enough.

Really this is just engineering. Every engineered structure in existence can take more weight than it ever does (well, except for the occasional screw-up); but the weight it takes is one that is established to be safe. Same thing with drugs.

The "occasional screw up" is one major reason FOR the safety factor.

But this is somewhat different from safety factors in engineering. While we might guess (and are probably right) that a drug is safe and effective past the expiry date (it's unlikely that we hit the real expiry right on, and it's likely it's a gradual dropoff anyway), we have no actual data to show that it is. This is different from safety factors in engineering, where we KNOW a design is adequate for say 2x it's estimated loading, because that is what we designed it to be because we might have miss-estimated the loading factor.

Or I should say, that is my understanding, I don't actually know how expiry date for drugs are estimated, I don't THINK that they empirically measure the effectiveness of the drug (either in vivo or vitro) at different points past manufacture time and choose the point in time where efficacy drops below a targeted amount. But I suppose it is possible that they do.