Voraxna was a type of lethal poison effective against Cardassians.
In 2373, Dukat had voraxna added to a bottle of kanar, which was then delivered to Tekeny Ghemor.
Benjamin Sisko later confronted Dukat and Weyoun with the poisoned kanar, which according to Sisko was enough to kill a dozen Cardassians. Weyoun drank the poisoned kanar, saying it was "quite toxic". Fortunately for him, however, Vorta were immune to most forms of poison. (DS9: "Ties of Blood and Water")