Transdermal fluoxetine (brand name Prozac)

One of my neutered male  cats has become a pisser, I've never had to deal with this before.  We can't get pills down him so the vet prescribed him transdermal fluoxetine to help with his anxiety.  The instructions say do not let it come in contact with your skin but the only way I can get it  in his ear is by putting it on my thumb and sneaking up on him and rubbing my thumb in his ear.  I tried looking up the side effects on humans but could find none.  Any vets or pharmacists out there that can help?  
I wash my thumb thoroughly after each application.  
Thanks