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Which drugs may worsen Myasthenia gravis?
Many routinely used drugs have adverse effects on the Neuromuscular Junction, which may not be significant in normal patients but can seriously worsen Myasthenia gravis.
The list is extensive, and the practitioner should be certain that a given drug does not have these effects before starting therapy in a myasthenic patient.
The list includes many antibiotics, particularly the aminoglycosides; cardiac drugs, particularly the beta-blockers (even Timoptic eye drops); chloroquine; phenytoin; lithium; magnesium; and excess doses of the anticholinesterases (cholinergic crisis).
Of course, neuromuscular blocking agents worsen symptoms and may prolong recovery and weaning from ventilation postoperatively, especially the depolarizing agents.
Rarely, drugs such as d -penicillamine may precipitate MG in previously unaffected patients.
A more complete list can be found on the website for the Myasthenia Gravis Foundation of America (MGFA) at www.myasthenia.org.
Drugs That Adversely Affect Neuromuscular Junction Function
| Antibiotics | Neuromuscular Blockers | Other Drugs |
|---|---|---|
| Aminoglycosides | Cardiac drugs | Phenytoin |
| Neomycin | Quinine | Chloroquine |
| Streptomycin | Quinidine | Trimethadione |
| Kanamycin | Procainamide | Lithium carbonate |
| Gentamicin | Trimethaphan | Magnesium salts |
| Tobramycin | Lidocaine | Meglumine diatrizoate |
| Other peptide antibiotics | Beta-adrenergic blockers | Methoxyflurane |
| Polymyxin B | — | Oxytocin |
| Colistin | — | Aprotinin |
| Other antibiotics | — | Propanidid |
| Oxytetracycline | — | Diazepam |
| Rolitetracycline | — | Ketamine |
| Lincomycin | — | d -Penicillamine |
| Clindamycin | — | Carnitine |
| Erythromycin | — | — |
| Ampicillin | — | — |
