Dimenhydrinate is a relaxant commonly found in sleep and health aids. In combination with other drugs, its effects can be overpowering. For this reason, it is used as a base for many different forms of tranquilizers.
There are antidotes known for several Dimenhydrinate based tranquilizers, all of which are members of the Thorazine family.
Mercury was armed with a weapon injecting Dimenhydrinate-induced darts, with which he shot Agent 5.