There’s no such thing as a 6 hour Oxycontin, only 12 hour (at least as far as indication goes). She may require it to be taken every 6 hours, but there isn’t a different formulation for it.
I guess it’s up to you if you want to find out what pill you have. You seem like you don’t want to bring it somewhere else because if it was a bootleg you don’t want to have this hassle of dealing with it? If the pharmacist is cutting corners you probably should notify someone, no?
Do they look like these?
