When we first took Fister to the vet, we had to sedate him to even get him in box. He got 10 mg. Plegicil. However, we didn't like the effect on him, it lasted for nearly 12 hours and he was completely zonked! We talked to our vet about it, and he suggested we try Diazepam (contains the same as Valium and Stesolid) 5 mg. of this is enough and he's a big cat (over 7 kg.) The effect is so much better and doesn't last as long.

Good luck!