I use advantix every month along with sentinel. The advantix is toxic to cats, so I keep my cat and Moca separated for 24 hours (vet recommended) after it's applied. My cat likes to give Moca lots of kisses
. The sentinel is used to prevent heartworm, but also breaks the flea life cycle. Sentinel isn't currently available, but my vet says it will be back on the market soon. Apparently, the plant where sentinel is manufactured also manufactures human medications. Because of the potential for stray human meds to be in with the sentinel, the plant is currently closed for inspection. Right now, I'm substituting sentinel with heartguard for heartworm prevention, but unfortunately, heartguard doesn't provide any protection against fleas.
Anyways, this combo has worked for me... I haven't had any flea problems (knock on wood).