My cat is on Buspar 10 mg/day. I give him a pill in the morning and at night. He was urinating every where so bad that I/we were considering getting rid of him. It's been a very trying summer. He's done it off and on for years, but it was getting to the point he wouldn't even use the litter box and he'd urinate/spray (even though he is neutered) the wall right in front of me, particularly in the basement. I even had him in a cage with his litter box and he refused to use it and I was coming home to a MESS everynight.
Needless to say he is no longer allowed in the basement. We just put down new carpet and plastered the walls and he was ruining it!!!!!
I started off giving the pill to him in a little piece of cheese, but that started getting old with him after a couple of weeks and he'd spit it back out. Now, I just pick him up, cradle him in one arm like a baby, use my other hand's finger to pry open his mouth and toss the pill towards the back of his throat, stroke his chin while keeping his mouth closed and down the hatch it goes!!!
Also, we are treating him sort of like a dog and have moved his cage and litterbox outside and he goes in and out to use it. When I ask our dog if she wants to go out, he also heads for the door. Actually, it's kind of funny!
I just don't know what I'll do this winter when the weather is too cold. I haven't thought ahead that far.
I asked the vet about any long term side effects and he said there aren't any and usually people just don't want the hassle of the pill or expense of it. I don't care about giving him the pill for the rest of the life if that's what it takes. Right now things have settled down and are going smoothly. A month ago, I'd have said he was a goner.
I'm sorry this was so long, but I hope it can provide you some help. Good luck! I know how frustrating it can be and I know how much you love your cat.