None, its just a new one. or I guesss you could say LSD or something.
No real drug. It's just some left-over coding from Oblivion that Obsidian wanted to use.
If it makes you see things that are really there, it isn't really a drug.
Since I become a vampire in Oblivion to use the Hunter's Sight spell which is basically amost the same effect as Cat's Eye, I would say that Cat's Eye is made from Vampire Blood, mixed with waste released from cats, and bacon. So yeah, basically its just a completely made up drug.