Voraxna

A Cardassian poison, Veraxa is extremely lethal to every species on which it has been used. Because of its strong, disctinctive odor and taste, it is generally put into similarly strong food or drink. Last Unicorn Games

In 2379, Madred used Veraxa poison to eliminate most of his competition among the Cardassian government. (Star Trek: Pendragon: "Exile")