Ziroxin-12, a poison with a very specific method of action, was available around the time of the Galactic Civil War. Zlarb was selling this poison on the planet Coruscant between 3 ABY and 4 ABY. Ochi of Bestoon, an assassin, went to Zlarb's establishment to get some poisons for an assassination job he was performing for Lady Qi'ra of Crimson Dawn. This job, the assassination of Emperor Palpatine's Royal Guard, necessitated a poison with a very specific timing, which led Zlarb to recommend Ziroxin-12 after Ochi mentioned this requirement.
Later, Ochi went to The Works District, where he instructed an ASN-909 to use the Ziroxin-12 to contaminate the breakfast of the Royal Guards; however, he observed that one of the guards was absent. The assassin subsequently located the missing guard, Major Erstin Deez, and because of the timing discrepancy compared to the poison given to the other guards, he was compelled to use Yurfloo instead.