Pyridostigmine, Neostigmine, Edrophonium

Summary

Pyridostigmine, neostigmine, and edrophonium are medications that treat myasthenia gravis by raising acetylcholine levels. However, if acetylcholine levels get too high, patients will experience cholinergic crisis, a syndrome caused by an overload of acetylcholine. This cholinergic overload can be reversed by administering atropine.

Key Points

• Pyridostigmine, Neostigmine, Edrophonium
  • Mechanism
    • Acetylcholinesterase (AChE) inhibitor
      • Increases acetylcholine levels in the myoneural junctions
  • Clinical Use
    • Myasthenia Gravis
      • Increases muscle strength
      • Underdosing of pyridostigmine can lead to a myasthenic crisis
      • Pyridostigmine is given in divided doses throughout the day, and should be taken at the same time every day
    • Reversal of neuromuscular blockers after surgery
    • Exposure to nerve gas
  • Side Effects and Adverse Reactions
    • Cholinergic crisis
      • In overdose
      • Increased secretions, bradycardia, miosis (pupil constriction), abdominal cramping, hypotension
    • GI disturbances
      • Nausea, vomiting, diarrhea, abdominal cramping
  • Antidote
    • Atropine