It isn't a US drug, had never heard of it but wow sounds great:
What does Vivitonin do?
Vivitonin contains the active ingredient propentofylline which is a xanthine derived compound. This means it is a similar compound to caffeine. Vivitonin increases blood supply to the heart and muscles. This means that Vivitonin can increase willingness to exercise and improves lethargy. It also increases blood flow to the brain which helps brain function and can help improve general demeanour and some signs of senility in older dogs. It can improve quality of life in older dogs but if a specific disease, such as kidney or heart disease has been diagnosed then that should receive specific treatment.
Could you give her an antacid about an hour earlier, give it time to work, then put the pill in cream cheese? Although it says before eating, enough to coat it should help. I know the other day I was retching when I got antirobe taste on my fingers. I am careful to make a pocket in the cream cheese, fold it over and give it to Arwen fast so she doesn't have to taste it cause if I let it sit, she refuses and I don't blame her!