After lots of research, I ordered Capstar from Petmeds.com. It arrived in record time, and I gave one of the small pills to my pup today. It is safe for pups and cats, and kills all adult fleas within 30 minutes. Doesn't kill the eggs though, but it is good to deter those adult fleas. Also safe to use with other treatments such as Frontline. I've managed to give it to my gentle cat as well as the pup. The other two cats...I don't know if they'll let me handle them enough to do this as you have to place the pill in the back of the throat.
All the pets are also treated with Frontline, and the pup got a second treatment, which seems to be working this time. Cats, not so sure!
Patty