Patient Safety: Impact of Antibiotics in Patients With Myasthenia Gravis

Published January 16, 2025

Practice

From the AANEM Quality and Patient Safety Committee

Neuromuscular junction transmission (NMT) has a high safety factor under normal circumstances. Conditions in which the NMT safety factor is impaired include myasthenia gravis (MG), hypocalcemia, hypermagnesemia, renal failure, infections, and concomitant use of drugs. Multiple medication classes have been implicated in exacerbating symptoms of MG. This include antibiotics (especially macrolides, aminoglycosides and fluoroquinolones) and other commonly prescribed drugs including beta-blockers, statins, magnesium, procainamide, etc. These medications can also precipitate MG crisis or unmask previously diagnosed MG. Awareness of a possibility of drug related MG exacerbation is very important as the interaction may result in severe morbidity and potentially a fatal outcome.

Question: Amongst the antibiotics used in MG patients, which one of the following has the risk of causing severe MG exacerbation?

A. Azithromycin
B. Penicillin
C. Ceftriaxone
D. Tetracycline

Explanation: Treatment of infections with antibiotics must be done cautiously in MG, given the risk of exacerbation with certain antibiotic classes. Documentation of anecdotal, observational and empirical data regarding specific medications led to the establishment of a list of Medications to be Avoided or Used Cautiously in MG patients (MAUC-MG). Infections were the most common factor (>50%) in MG exacerbations. MAUC- MG were factors in 19% of the recorded exacerbations and approximately 20% of exacerbations happen within 30 days of prescribing MAUC-MG. Of the antibiotics, macrolides, Fluroquinolones, and Aminoglycosides, are most well-recognized to precipitate or worsen MG, and should be avoided if possible. The US FDA has designated black box warning for using Fluroquinolones and Telithromycin. Due to limited report of side effects after Penicillin use in MG patients, it is one of first line antibiotics to treat infections in MG patients. Reported side effects after the use of cephalosporins, sulfa drugs, tetracyclines, polymyxin B and nitrofurantoin, clindamycin are rare or very few in the form of occasional case reports or in-vitro studies. These drugs can be administered safely to MG patients. 

Authors: Banu Sundar, MD; Lee Murray, MD; and Charles Kassardjian, MD

Sources:

  1. Drugs That Induce or Cause Deterioration of Myasthenia Gravis: An Update Shuja Sheikh, Usman Alvi, Betty Soliven and Kourosh Rezania J. Clin. Med. 2021, 10, 1537. https://doi.org/10.3390/jcm10071537
  2. Factors associated with acute exacerbations of myasthenia gravis Rohit Reddy Gummi Natalie Anna Kukulka Chelsea B. Deroche Raghav Govindarajan Muscle & Nerve. 2019;60:693–699 DOI: 10.1002/mus.26689
  3. https://myasthenia.org/Portals/0/Cautionary_Drugs_2020.pdf