The evidence for the effectiveness of pyridostigmine bromide as pretreatment against soman-induced toxicity was derived from animal studies alone. [See Nonclinical Toxicology (13.2).]

Pyridostigmine bromide is for use as a pretreatment for exposure to soman nerve agent. Pyridostigmine bromide alone will not protect against exposure to soman. The efficacy of pyridostigmine bromide is dependent upon the rapid use of atropine and pralidoxime (2-PAM) after soman exposure.

The primary protection against exposure to chemical nerve agents consists of wearing protective garments including masks, hoods, and overgarments designed specifically for this use.

Individuals must not rely solely upon pretreatment with pyridostigmine bromide and the antidotes atropine and pralidoxime (2-PAM) to provide complete protection from poisoning by soman nerve agent.

Pyridostigmine bromide must not be taken after exposure to soman. If pyridostigmine bromide is taken immediately before exposure (eg, when the gas attack alarm is given) or at the same time as poisoning by soman, it is not expected to be effective and may exacerbate the effects of a sublethal exposure to soman. [See Clinical Pharmacology (12.2).]

The dose of pyridostigmine bromide is one 30-mg tablet every 8 hours, started at least several hours prior to exposure to soman. At the first sign of nerve agent poisoning (runny nose; watery eyes; small, pinpoint pupils; eye pain; blurred vision; drooling and excessive sweating; cough; chest tightness; rapid breathing; diarrhea; increased urination; confusion; drowsiness; weakness; headache; nausea, vomiting, and/or abdominal pain; slow or fast heart rate; and/or abnormally low or high blood pressure), pyridostigmine bromide should be discontinued and treatment with atropine and pralidoxime should be instituted immediately.

There is no known advantage to taking pyridostigmine bromide just prior to or concurrent with soman exposure. According to the mechanism of action of pyridostigmine bromide [See Clinical Pharmacology (12.2)], pyridostigmine bromide is effective when it is given sufficiently in advance of soman poisoning to provide a pool of protected enzyme. Therefore, it is expected that pyridostigmine bromide will not be effective if administered just prior to or during exposure to soman.

The benefits and risks of use beyond 14 consecutive days have not been definitively established; therefore, continued use beyond 14 consecutive days should be evaluated in the context of the likelihood of exposure to soman nerve agent.