drugs for spraying neutered cat

Question
I have had my cat on Clomicalm for a couple of years but it is not preventing him from spraying. He will go a week or so without spraying and then BOOM -- he sprays twice in one morning. And I am religious about pilling him. I have him tested regularly for urinary tract infections. My vet just thinks he is a high-strung cat.

Since Clomicalm is not working for him, is there another medication that might work? You mentioned Prozac and Evalil(?) in an earlier post but it was not clear to me which one of these was the most effective. I need the number one, most effective medication for stopping spraying.

I am at my wits end -- spending two days ripping up urine soaked carpeting that I now need to replace but don't want it soaked again. I hate to say it, but I have thought about having him put down. He has sprayed every small appliance (coffee maker, toaster oven, grill, microwave) on my kitchen counters and every single piece of furniture I own. I am exhausted and fed up. As much as I love this kitty, my patience over the past 3 years has been sorely tested and is about to run out. Help!!

Answer
As with most thing, there is not one medication that works best in every single case.  Overall, Prozac has been proven most effective for spraying.  Nearly 90% of cases improved or were resolved with the use of Prozac.  Elavil is successful in a little over 70% of cases.  But should Prozac not work, I would still recommend giving Elavil a shot.

Also, some cats will benefit from the use of megestrol acetate (Ovaban).  It's a female hormone that can help stop male cats from spraying.  It should be used only short term, less than 2 months, because serious side effects like diabetes and mammary cancer, even in males, are extremely common if used long term.  Fortunately, if the medication is going to work, you should see improvement within a couple of weeks.