It is probably fine. I would only drink it if you were the one who has been storing it this entire time. I'm not trying to say this is completely against the rules or anything, but we would not be able to tell you for fact that it is safe to drink without actually analyzing it in a lab to determine there is nothing wrong with it. The same would go for someone asking if the Milk in their fridge is safe to drink. Sure, we can say, "probably" it's okay after 3 days, but there could also be E. Coli in that milk simply at random and we couldn't safely tell someone to drink that milk with a clear conscience, without knowing that it factually is safe to drink. The same goes for your Methadone. That is a personal choice for you to make based upon what you know about the solution. I'm not saying I'm opposed to answering this, it's just that it can't be answered safely without evidence.
Closed.