The Rossak drug was a simple name of an incredibly potent toxin, a chemical so deadly discovered by the pharmaceutical scouts and Aurelius Venport.
Once administered, the Rossak drug was always fatal, even in minuscule doses. The chemical had no legitimate uses outside of the assassin's trade. No known antidote had ever been found.
During the Rossak Epidemic, Raquella Berto-Anirul and Mohandas Suk tried to find a cure with the cenote water. Dr. Suk created a vaccine based on the water elements, however Supreme Sorceress Ticia Cenva used the drug secretly to kill the test subjects who had received it. Ticia intended to discredit the HuMed who dared to claim they were better healers than the Sorceresses themselves.