%mithridate%

n. (Med.) An antidote against poison, or a composition in form of an electuary, supposed to serve either as a remedy or a preservative against poison; an alexipharmic; -- so called from King Mithridates, its reputed inventor. [ 1913 Webster ]

[ Love is ] a drop of the true elixir; no mithridate so effectual against the infection of vice. Southey. [ 1913 Webster ]