I got this idea from a friend, I have a girl on meds who mostly refuses them on treats, mixed with yummy foods, etc
I put the meds on her paw (and arm) and she has to lick it off
it's not perfect but it's getting the meds into her and she's finally starting to sound better
It was bit easier for me because I'm mixing pills with water at home, didn't get the stuff already mixed from the vet, so I can concentrate the dose so I don't need to use as much
if you have someone to help you, forcing the meds may work, let me see if I can find the video of how it's done
It's hard for one person to do if you have a rat who really fights it, but if you're strong and quick you might be able to do it
here's the video by lilspaz/ Shelagh
https://youtu.be/w-_bFMkutKk
also there's a thread here on different things to mix the meds into, believe me I've tried them ALL but Cool whip worked pretty good a couple of times
with a smart rat you may need to vary the foods you use, cuz they catch on pretty quick
another thing that sometimes works with my girl is to put the meds on a bit of whole grain bread and mush it into a bread ball. she likes those, but will refuse it if she's just recently eaten, so timing matters! be sure not to give any treats beforehand lol
you might also have to withhold food for an hour or two (or more..?) before the meds are due to be given, so that your rat is hopefully hungry enough to accept the med/treat combo