She will be on the right drug cocktail to keep her alert and calm for a couple of hours before they wear off. She will be out of sight before the side effects kick in.
Methinks her behavior is beyond the ability of some drug cocktail to mask it. Because if such a cocktail existed, there'd be no need for her to wait until the debates to take it. She would have been taking it at all of her other campaign appearances as well, in order to stave off any questioning of her stability.