MG in pregnancy

Q; 32 years old female in the first trimester of pregnancy is admitted to ICU with exacerbation of her Myasthenia Gravis (MG). The patient is started on pyridostigmine. This patient might require? (select one) 

 A) higher dose

 B) lower dose

Answer: A

Pyridostigmine i.e., acetylcholinesterase inhibitors stays the standard first-line treatment for MG in pregnancy. But, it may require a higher dose as renal clearance goes up in pregnancy, there is an expanded maternal blood volume, and frequent emesis. The important thing is to remember to decrease the interval of administration. Later, increase the dose if symptoms persist. Said that caution should be taken to avoid intravenous (IV) pyridostigmine just prior to delivery as it may cause uterine contractions.

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References:

1. Stafford IP, Dildy GA. Myasthenia gravis and pregnancy. Clin Obstet Gynecol 2005; 48:48.

2. Norwood F, Dhanjal M, Hill M, et al. Myasthenia in pregnancy: best practice guidelines from a U.K. multispecialty working group. J Neurol Neurosurg Psychiatry 2014; 85:538. 

3. Sanders DB, Wolfe GI, Benatar M, et al. International consensus guidance for management of myasthenia gravis: Executive summary. Neurology 2016; 87:419.