Primary treatment for Tabun and several other nerve agents is Atropine Sulphate. It is commonly carried in auto-injectors by military personnel in dosages of 1-2 mgs. However, in many cases, massive doses may be necessary to reverse the effects of the anticholinesterase agents. Frequently, 20-40 mg of atropine may be necessary.
Atropine is derived from deadly nightshade Atropa belladona. It is a raecemic mixture of (+) and (-) hyoscyamine, the (-) or laevo isomer being much more potent. It has its action on peripheral post-ganglionic parasympathetic acetyl choline receptors.
The second drug that is used in the treatment of "nerve gas" poisoning is Pralidoxime chloride (3-PAMC1). It is used to reactivate the the acetylcholinestrase that is bound by the nerve agent. The dosage for 3-PAMC1 is normally 600mg per injection and that it may have to be given repeatedly. Therapeutic levels may also include 1 or more grams of Pralidoxime to be given by intravenous administration over an eight hour period.