The small box of Interceptor has a cat on it as well. . .evidently it's also given to cats, but at a higher dosage per-pound for cats than for dogs (green box is labeled for dogs 11-25 pounds, cats 1.5-6 pounds). So I think it's safe, unless your cat is sensitive to the ingredients.
If you've microchipped your cat through HomeAgain AND you've paid the yearly payment, you can call their 1-800 # and get free poison control type help.