II. Indications
- Pretreatment before Nerve Agent Exposure (Soman)
- Pyridostigmine does not protect against exposure
- Nerve Agent Exposures must be treated with Antidote (e.g. Pralidoxime chloride, Protopam chloride)
-
Myasthenia Gravis
- Provides symptomatic relief, esp. extremity weakness and bulbar symptoms
- Less effective on Ptosis and Diplopia
- Unlikely to benefit myasthenia crisis with Respiratory Failure and may interfere with respiratory management
III. Physiology
- Pyridostigmine is an Anticholinesterase
- Results in increased Cholinergic effects
IV. Dosing: Nerve Agent Exposure
- Pyridostigmine 30 mg PO every 8 hours before exposure
-
Pharmacokinetics
- Significantly enhances post-exposure antidote for Soman
- Does not enhance antidote for other Nerve Agents
- Raises SomanLD50 by several fold
V. Dosing: Myasthena Gravis
- Child: 0.5 to 1 mg/kg every 4-6 hours (maximum 7 mg/kg/day divided every 4 to 6 hours)
- Adult
- Starting Dose: 30 mg three times daily
- Typical Dose: 60 to 90 mg every 4 to 6 hours while awake
- Maximum Dose: 120 mg every 4 hours while awake
- Doses exceeding 120 mg every 3 hours are not more effective
-
Pharmacokinetics
- Onset: 15-30 minutes
- Peaks: 2 hours
- Duration: 3-4 hours
- Precautions
- Not often effective as monotherapy in Myasthenia Gravis
VI. Adverse Effects
- Risk of worsening myasthenia crisis (due to mucous plugging, bronchorrhea)
- Risk of Cholinergic Toxicity (esp. at higher dose)
- Gastrointestinal side effects
- Muscle Fasciculations
- Eye tearing
VII. References
- (1998) USAMRICD Chemical Casualties Handbook, p. 58-9
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