My name is***** and I am sorry to hear that your kitty is so lethargic. Just to clarify, you gave the Buprenorphine at 11pm and after that she became lethargic? Buprenorphine does not usually cause sedation, but that doesn't mean that your kitty isn't more sensitive to its effects. The sedation and lethargy should wear off in 2-4 hours.
Meloxicam and Revolution do not have any sedative properties, so I would not suspect those meds.
For this evening, I would recommend watching your kitty closely. Do not allow her to sleep on something cold like a tile or cement floor, keep her on a warm bed but don't wrap he up unless her body temperature drops below 100 degrees. (you can take a kitty's temperature via rectum with a standard digital thermometer. Normal temperature for a cat is 100.5 to 102.5).
In the morning, I would very gently touch your kitty's paws to see if she is still painful. If she cries or pulls her paws away, you can assume she is painful and I would give more buprenorphine to keep her comfortable.
I hope this answer helps you. Feel free to contact me if you have any further questions.
Kansas State University
College of Veterinary Medicine Class of 2001