Nerve Agent Antidote Pyridostigmine Bromide PB

PB is used in the US Army as an antidote against the nerve gases sarin and soman (Fig. 4.25). PB is not a vaccine. As a 90-mg dose taken before a nerve gas attack, it increases the efficiency of other antidotes. The use of PB was approved by the FDA for this purpose in 2003 (12 years after the First Gulf War). Another medical use of PB used since 1955 is in treating a disease named myasthenia gravis, where the necessary daily dose is 1500 mg ( ). PB inhibits an enzyme called acetylchohne esterase, so it slows down the decay of the nenrotransmitter acetylcholine. Acetylcholine is a physiological antidote of adrenaline, and is formed at sites where there are parasympathetic nerve impulses. Acetylchohne dilates peripheral blood vessels, lowers blood pressure, slows down heartbeat and intensifies gastrointestinal motility. Its effect is short-lived as the enzyme acetylcholine esterase hydrolyzes it to chohne and acetic acid. 

About half of the veterans of the First Gulf War received PB tablets before combat An epidemiological study of myasthenia gravis and the Gulf War Syndrome showed that PB alone is not likely to have caused the syndrome, but may be a contributing factor in the presence of other risk factors. 

---