I'm kind of the 'mean scary nurse' type when it comes to medicating rats... I just don't have the patience to beg them to take something. My girls LOVE the baytril I get from the vet - because it's suspended in butterscotch flavor. The boy still hated the stuff. No interest whatsoever. Also hated the berry flavored motrin he had after surgery. I got him to eat the meds if I mixed it with some bolongese baby food, but it just became a pain in the butt, so I'd scruff him quick, squirt in both meds, and be done. He eventually just let it happen instead of fighting me, because he knew it would be over sooner that way.
I have to give meds to various animals on a given day at work (pet store), including rats which are unsocialized and don't give one hoot about the butterscotch flavoring. They also wont touch any 'strange' foods, if I were to try and mix meds with food. Instead, I have to be persistent, but quick, so they don't get too stressed.
I'm fortunate that the baytril is flavored in the first place, and that the girls push each other out of the way to try to get to the other's syringe (at one point, they both had a URI at the same time, and they'd race to get done and run over to the other one to steal their 'treat').