Pyridostigmine Bromide

Pyridostigmine bromide (PB) is a drug the Food and Drug Administration approved in 1955 to treat myasthenia gravis, a neuromuscular condition characterized by weakness and muscle fatigue.

Soman is a chemical warfare nerve agent that acts by inhibiting the action of the enzyme cholinesterase, needed for muscles to function properly.

In experiments conducted with primates, pyridostigmine bromide showed it was effective in protecting against soman's lethal effects. However, there is no ethical way to test its efficacy in humans because doing so would require actually exposing humans to soman.

During the Gulf War, the US intelligence community believed the threat of Iraq's using nerve agents was very strong, based on that country's proven use of nerve agents during the Iran-Iraq War (1980-1988). A specially constituted Food and Drug Administration (FDA) human-use review committee carefully deliberated and decided pyridostigmine bromide could help save the lives of many servicemembers if nerve agents were used.

Based on extensive scientific information, the FDA approved using pyridostigmine bromide as an "investigational new drug" as a pretreatment adjunct to protect US and some allied military personnel from death in a chemical warfare agent attack using soman. The drug's use was classified as "investigational" because it was being used for a purpose other than its approved licensed use. It is a pretreatment adjunct because it must be given before exposure to soman to be effective. It is not effective alone but is beneficial only if appropriate treatment is given after exposure.

Recommended doses were lower than those commonly used to treat myasthenia gravis patients, but no good records exist of the amounts servicemembers actually took. Scientists say without knowing the dosage or amount of exposure to a drug or chemical, it may be impossible to determine its impact on health over time.

In 1999, the RAND Corporation released a report indicating pyridostigmine bromide could not be ruled out as a contributor to the development of some Gulf War veterans' unexplained or undiagnosed illnesses. Secondly, the study also noted that uncertainties remain about the effectiveness of pyridostigmine bromide in protecting humans against chemical warfare agents.

More recently, an Institute of Medicine committee reported its studies indicate the evidence is insufficient to determine if pyridostigmine bromide can be associated with long-term health problems.

Because of these uncertainties about pyridostigmine bromide, the Department of Defense has committed more than $14.7 million to 19 research projects aimed at better understanding pyridostigmine bromide's safety and effectiveness.

In 1998, Congress passed legislation stipulating only the President can authorize the military use of pyridostigmine bromide without informed consent to save the lives of troops facing exposure to soman.

All Gulf War veterans are eligible for a free, comprehensive medical evaluation. DoD has established the Comprehensive Clinical Evaluation Program for Gulf War veterans still on active duty, serving in the Reserves or those who are retired from military service. Those veterans should call (800) 796-9699 to schedule an appointment. The Department of Veterans Affairs administers a similar program for all other veterans, who can call (800) 749-8387 to schedule an evaluation in that program.

More detailed information on pyridostigmine bromide and other projects of the Office of the Special Assistant is available on the Internet at GulfLINK.