Thats interesting, idk the similarities or differences in our meds and obviously im not a doctor but you are the first person to mention this breakiing down problem. Maybe its more likely for valerate??
But cypionate (what im on) seems to be shelf stable for years. The consensus ive been hearing is when its open its good for about 6 months safely. Ive heard mention of people going longer, but those are outliers and most agree 6 months is a good rule. I believe at my dose 6 months would make an empty vial.
You have the same concerns i have. I see stories every so often on here of people struggling to get doctors, clinics, pharmacist, psychs etc etc to believe in their transness. Some people it takes years! So i does hurt to throw it away.
Which is why ultimately i wont be doing that. Might use till gone and build a backstock, might donate. Idk yet.
Like i said, not a doctor, but if youre feeling and thinking the same as me then i say its worth doing research into it and seeing if there is something you can do. โค๏ธโค๏ธ