I notice it gets washed out quick by looking the water. Could always soak in the fridge for 24hrs and then freeze. I get a needle and syringe and inject some vitachem into the pieces and works for me.
Freeze dried krill will soak up meds quickly, but once it hits the water, the liquid meds slowly leak out. If the fish immediately eats the freeze dried food, then fish should be getting most of it.
What medication are you trying to get the fish to eat?