Drugs to Avoid in Patients With Myasthenia Gravis


A comprehensive review of drugs to avoid when designing treatment plans for patients with myasthenia gravis.

Dr. James F. Howard: With myasthenia, they're not immune to other diseases. And so, are there classes of drugs that pose risks to the patient in your experience?

Dr. Nicholas J. Silvestri: I think the biggest class of drugs, the biggest category of drugs that I worry about are antibiotics specifically aminoglycosides, which are contraindicated in patients with MG, but even the fluoroquinolones; drugs like ciprofloxacin, levofloxacin I've seen people worsen on. I always tell my patients when we make the diagnosis or perhaps at the second visit there are medications you need to be mindful of. And the biggest class in my mind are the antibiotics. If you need to be on an antibiotic, please run it by me first. It is a bit of a nuisance for them or their primary care doctor, but I think it's well worth it. It is well worth a few minutes of our time to get on the phone and have that discussion to avoid any worsening for something that could have been avoided. After all, there are enough antibiotics out there that do not aggravate myasthenia, that you can always find something that has, I think, similar coverage for that particular infection. And I would say the other class that I'm somewhat mindful of are some anti-hypertensives, beta-blockers in particular, I've seen have worsened some patients that I take care of. Frankly, if you go onto a reputable source and look at the list of drugs that can worsen myasthenia, they're really all on there. I always like when the EMR tells me that prednisone and pyridostigmine are contraindicated in myasthenia. Clearly went to a better medical school than I did, but notwithstanding, those are the two classes I think about, and I think others are certainly on there, but it's more of, I take those with more of a case-by-case basis.

Dr. James F. Howard: The most common drug that precipitates a hospital admission for an exacerbation from an antibiotic perspective is azithromycin, Z-Pack. And we have more patients who are put on that, who then end up in the hospital. And so, that is a bad actor. The other one that as you said, the beta-blockers, and I've seen it with ocular Timolol, for instance, when it was quite prominent in days past. The installation of B topic, which was the similar oral agent precipitated myasthenia crisis in a woman. And so, these are readily absorbed and have different mechanisms of action at the neuromuscular junction. Some are presynaptic blockers, some are postsynaptic blockers, and then to give myasthenic patient a calcium channel blocker, you've just given them a double whammy. The release of neurotransmitter as well as an antibody blocking the receptor. And we've had numbers of patients get into trouble. Notwithstanding, our rules are that if there's an alternative, you use it. If not, know that you may get into trouble and you have to use it, and then we're on standby. And then within a drug class, there are some that are less toxic than others. And you go to the one that has the least potential toxicity. I guess another question - we'll come back to that.

Transcript Edited for Clarity

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