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Pyridostigmine bromide |
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| Agents targetted | Soman (GD) |
| Generally effective against | Used therapeutically in the treatment of myasthenia gravis and in aiding recovery from certain anesthetics. It is approved for use in the prophylaxis of exposure to Soman. |
| Available forms | Oral (tablets, prolonged release tablets and syrups), injection |
| Indications and usage | Oral pyridostigmine is used as a prophylactic for possible exposure to soman. If there is a threat of use of soman, pills are taken three times a day, preferably under supervision of a medical officer. Maximum use is 1-3 weeks. Oral pyridostigmine is poorly absorbed and it can take several days to build up a therapeutic concentration. |
| Contraindications | Use of pyridostigmine must stop as soon as soman is detected. Any known adverse response to other anticholinergics, such as obidoxime, physostigmine, edrophonium, neostigmine and ambemonium, is a contraindication. Asthma, irregular heartbeat, slow breathing and bladder or bowel blockage should be reported before beginning pyridostigmine use. Bromide allergy is also a contraindication. |
| Drug interactions | Avoid the use of alcohol and anything that may make you sleepy, including sleeping pills, over-the-counter cold and allergy medicines, strong pain killers and tranquilizers such as thorazine or Mellaril. There is also a possible interaction with the anti-malarial mefloquin. Herbal products should not be taken. Succinylcholine should not be used as a muscle relaxant in surgery if the patient has been exposed to pyridostigmine. There is no information on adverse effects in pregnancy and children. |
| Adverse
reactions and side effects
NOTE: all such reactions are rare. |
Commonest adverse effects are:
Indications of an overdose requiring urgent response include:
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| Mode of action | Pyridostigmine is a reversible inhibitor of acetylcholinesterase. It sequesters a fraction of the enzyme in the peripheral nervous system that will support normal function until atropine and oximes can be administered. However, if pyridostigmine is administered after soman exposure, the lethality of the nerve agent is increased. |
| Structure |  |
| Chemical names |
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| CAS Registry number | 101-26-8 |
| Notes and Comments | Oxime prophylaxis has been a component of chemical defense protocols for decades and the current recommendation for the use of prophylactic pyridostigmine is approximately 100 mg/day for a maximum of 7 days. This is much lower than the levels used in the treatment of myasthenia gravis since 1955 (600 mg/day). It was issued to US forces during the 1990-1991 Operations Desert Shield and Desert Storm. Of approximately 40,000 who took the drug, about half experienced mild gastrointestinal problems and 28 had to discontinue use because of more severe adverse effects, including exacerbation of asthma and allergy, hypertension, and severe gastrointestinal complaints. The total number of troops using pyridostigmine was approximately 300,000 (250,000 US and 50,000 British.) In the aftermath of the war, many soldiers developed unexplained and complex health problems that became known as Gulf War Syndrome. A number of causes have been suggested, although none explain all of the symptoms observed. Pyridostigmine has been suggested to have been one of the causes. This is complicated by the fact that it was only approved by the US Food and Drug Administration for use in the prophylaxis of nerve agent exposure in February 2003. Even then, it was only approved under a rule known as the animal efficacy rule that had first been issued in June 2002. The rule allows the use of a drug after animal tests, but without the mandated human tests if they cannot be ethically or feasibly conducted. |
| (known and reported, not all may be current.) |
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| Trade Name | Country |
Kalimin |
Germany |
| Mestinon | USA |
| Regonol | not known |
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