She takes the drug to keep from having an episode and end up drooling on the stage floor in front of 60 million people
I bet all those 12k heavy rug style coats she has begun wearing are concealing quite a bit for her public appearances.
She may have a port-line installed or an IV line that is administering continuous fluids and medication. She also could be having her vitals remotely monitored back stage via telemetry. (If she heads south, they could intervene with some bogus interruption and preempt another damaging collapse.) She may be using a foley catheter to contain the fluid output.
Trump is correct in his observations of her unhealthy demeanor and boosted debate performance.