Meds often expire long before they actually decay. There are a variety of reasons for this:

• the drug makers want waste; just like printer ink makers they want to sell you more than you need in part by encouraging waste.
• performing rigorous tests on the rate of decay of drugs to get an accurate expiry date is costly. It’s much cheaper to skip the testing and choose an arbitrary date that is obviously safe. The excessively big safety factor that results supports the 1st point.
• liability for overestimating the expiry is costly.

So I rarely use even ½ a prescription following an incident. But then I’ll often take expired drugs knowing that the expiry date is often arbitrary anyway. Many drugs do not become more dangerous past the date; they just lose potency and need more of a dose (depending on the drug). Anyway, I digress.

The main problem is the excessive controls. You can’t openly resell what you don’t use. Pharmacies don’t want it back and you’re stuck with it.

India has started a “shared doctor appointment” scheme. The idea is that if you have a dozen people with the same medical condition and the doc’s time is limited, they have introduced an option to have everyone meet at the same time to learn about their condition, almost like taking a class. Some patients then establish friendships with other patients with the same condition. Well why not share the meds considering these patients would often have the same prescription?