Psychiatric Drugs Contraindicated in Myasthenia Gravis

Primary Psychiatric Medications to Avoid

The American College of Neurology recommends avoiding barbiturates, particularly butalbital-containing medications like Firocet, in patients with myasthenia gravis due to their potential to worsen neuromuscular transmission and exacerbate muscle weakness, potentially leading to respiratory compromise 1
Barbiturate-containing medications pose particular risk for respiratory compromise in patients with active, symptomatic myasthenia gravis 1
If barbiturates must be used, close monitoring is required for worsening muscle weakness, respiratory compromise, and changes in bulbar function (speech, swallowing) 1

The American Academy of Neurology suggests that β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides should be avoided in patients with myasthenia gravis due to potential exacerbation of symptoms 2, 3
Macrolide antibiotics specifically can worsen myasthenia symptoms and should be avoided 3
Fluoroquinolone and aminoglycoside antibiotics pose similar risks 3

Approximately 50% of patients with ocular myasthenia may develop generalized myasthenia within a few years, requiring ongoing vigilance 2

Before prescribing any potentially problematic medication, assess current symptom control, disease stability, and respiratory function (vital capacity and negative inspiratory force) 1
Regular pulmonary function assessment is crucial in patients with generalized myasthenia gravis to monitor for respiratory compromise 2, 3

For pain management requiring psychiatric medications, consultation with neurology is recommended before initiating any new medication to determine the safest alternatives 1
SSRIs may be used cautiously in myasthenia gravis patients, though they are not specifically contraindicated, according to the American Academy of Child and Adolescent Psychiatry 4

If a potentially problematic medication must be used, monitor for worsening muscle weakness, respiratory difficulties, changes in speech or swallowing (bulbar symptoms), and double vision (diplopia) 3

Methocarbamol is contraindicated in myasthenia gravis as it interferes with the effects of pyridostigmine bromide, the primary treatment for MG, according to the Mayo Clinic Proceedings 5
Orphenadrine is also contraindicated in myasthenia gravis due to its anticholinergic properties, as stated in the Mayo Clinic Proceedings 5
These medications can directly antagonize the therapeutic effects of acetylcholinesterase inhibitors used to treat MG, as reported in the Mayo Clinic Proceedings 5
Benzodiazepines can be used cautiously for anxiety and insomnia in myasthenia gravis, but require careful monitoring for respiratory depression, particularly in patients with bulbar or respiratory muscle involvement, as recommended by the American Academy of Family Physicians 6
Infrequent, low doses of benzodiazepines with short half-lives (lorazepam, oxazepam, temazepam) are least problematic, according to the American Academy of Family Physicians 6
Regular use of benzodiazepines can lead to tolerance, cognitive impairment, and paradoxical agitation in approximately 10% of patients, as noted by the American Academy of Family Physicians 6

Trazodone can be used for agitation and insomnia in MG patients, starting at 25 mg daily with maximum doses of 200-400 mg daily in divided doses, as recommended by the American Academy of Family Physicians 6
Use of trazodone should be with caution in patients with premature ventricular contractions, as advised by the American Academy of Family Physicians 6
Divalproex sodium is generally better tolerated than other mood stabilizers, with initial dosing of 125 mg twice daily titrated to therapeutic blood levels (40-90 mcg/mL), as stated by the American Academy of Family Physicians 6
Monitor liver enzyme levels with divalproex sodium, as recommended by the American Academy of Family Physicians 6