I can only, for some reason, get my vet to give me the inject able as well. It says to mix 1ml Baytril into 250mls water or tang but doesn't say how much they need per day. I'll have to ask about that... hmmm... anyhow, here's what I do, and it's a huge, HUGE hit with the ratties:
(I use the narrow syringe, no needle, with a Baytril bottle fitted with a blue cap that the syringe fits into so I can tip it over to measure the meds)
.1ml (point one milliliter) Baytril
5.5 teaspoons water
a sprinkle of UNSWEETENED kool-aid
swirl in the water bottle and serve
I found that Tang and sweetened kool-aid clogged the water bottle and caused it to leak out into the cage. Juice doesn't work either because it goes bad if it sits out too long. The instructions they give you (250ml of water) makes it impossible to change the water daily.