Neostigmine and Pyridostigmine Dosing for Myasthenia Gravis

Introduction to Acetylcholinesterase Inhibitors

The American College of Oncology recommends pyridostigmine as the first-line acetylcholinesterase inhibitor for myasthenia gravis, with neostigmine reserved for situations where oral administration is not possible, using a conversion of 30 mg oral pyridostigmine = 1 mg IV neostigmine or 0.75 mg IM neostigmine 1

Pyridostigmine is the standard acetylcholinesterase inhibitor for myasthenia gravis, with dosing ranging from 30 mg to 600 mg daily in divided doses 1
The typical dosing regimen involves multiple daily doses to maintain consistent symptom control throughout the day 1

In myasthenic crisis, pyridostigmine may be discontinued or withheld, particularly if intubation is required 1
30 mg oral pyridostigmine = 1 mg IV neostigmine = 0.75 mg IM neostigmine 1

The Anaesthesia society recommends evaluating the TOF ratio by EMG before administering any muscle relaxants in myasthenic patients 2
If the TOF ratio is <0.9 before neuromuscular blockade, sensitivity to muscle relaxants is significantly increased and doses must be reduced by 50-75% 2
Sugammadex is preferred over neostigmine for reversal of steroidal muscle relaxants in myasthenic patients to avoid interference with long-term acetylcholinesterase inhibitor therapy 2

Never use neostigmine dosing guidelines intended for anesthetic reversal (40-70 mcg/kg IV) when treating myasthenia gravis—these are completely different clinical contexts with different dosing requirements 3, 4, 5