I'm no expert but I don't see why not. The only problem you might have, is that meds often reduce the oxygen carrying capacity of the water - so a bit of extra aeration might help.
I wouldnt be worried about melafix at all. It doesnt need an increase in oxygenation like some meds do. I wouldnt say that you can use all meds though but with the use of a airstone you could probably use most without a problem.