Pharmacology and toxicology of chemical warfare agents

Toxic chemicals have been used as weapons of war and also as means of terrorist attacks on civilian populations. The main classes of chemical weapons are: a) nerve agents, b) vesicant agents and c) blood agents. If an exposure to nerve agents is anticipated, prophylactic pyridostigmine may be used. Once exposure has occurred, the management strategy is to reduce cholinergic activity through the use of atropine as well as to attempt to regenerate acetylcholinesterase with pralidoxime. Convulsions may be managed using diazepam. Exposure to vesicant agents may be reduced through the use of protective gear, but once exposure has occurred, no specific treatment is available. Treatment remains symptomatic and supportive. Lethal atmospheric concentrations of hydrogen cyanide gas, a blood agent, is seldom achieved except in enclosed spaces. Sub-lethal exposure to hydrogen cyanide may be managed using sodium nitrite, sodium thiosulphate and VitB12.