This issue is a conundrum. Most drugs don't fall off a cliff of efficacy when they reach their expiration date. There are drugs such as tetracyclines that should never be used past their expiration dates because they degrade into toxic compounds. Certain classes of drugs such as anti-arrhythmics or drugs like warfarin are dosing critical to the point where I would not want them if they were out of date. I worked in p…
I think that a better approach to 'expiration dates' should be that highly controlled dispensaries (pharmacies) track lot and production dates. A given medication should have a standard expiration date based on /observed/ potency and reserving a safety factor (which should be known and recorded).
Drugs before the typical expiration date would have very infrequent random samples tested for effectiveness. If there is economic or technical incentive, medications nearing the expiration date would be tested and based on the results a new expiration date and testing schedule for the remaining units set.