The main selling point of them was that they were extremely fast to use. I don't think it'd be OP at all. Especially if you want to add donor versions of these. Players should be able to choose what meds they want.
Most players would still use regular meds because they have the biggest heal. Some people use sodas because they are fun and heal both hp and ap, and some people would use vials and pills for instant recovery. All 3 types have their benefits and flaws. Buff to 1500 delay would be great. I think it was 1000 before they were removed?
I will still use them anyway, I see why you went with such high delay but I don't think it's necessary, it doesn't have to be made spammable, but rn the delay is so long it just doesn't feel good