Atroxium is a fully functional nerve gas which when inhaled leaves its victims in a terrifying permanent nightmare induced state that they can only be released from them by taking the antidote. The gas was invented through years of self testing by Dr. Stanley Wheelwright and was first seen in "Chuck Versus the Aisle of Terror".
The first time we see the drug used was when Dr. Stanley Wheelwright uses the drug on a Volkoff Industries's guard when the guard questions him about being in a restricted area. The assault of the guard turns out to a demonstration of the drug to Mary Bartowski who agrees that it's time to sell the drug.
Presumbly a play of some order on the notion "atrocious".