Drugs to avoid or use with caution in myasthenia gravis

Certain drugs (see Drugs to avoid or use with caution in myasthenia gravis) must be avoided or used with caution in patients with myasthenia gravis, because they can make the symptoms worse. Monitor the patient whenever they start a new drug, especially when the drug has adverse effects of weakness or fatigue. Closely monitor myasthenia gravis patients for hypothyroidism, hyperthyroidism and electrolyte imbalances (eg hypermagnesaemia, hypokalaemia), as these conditions can exacerbate myasthenic symptoms. Some drugs have been reported to cause myasthenia gravis (eg case reports implicating ipilimumab, as monotherapy or with nivolumab).
Table 1. Drugs to avoid or use with caution in myasthenia gravis

[NB1]

Printable table

Avoid

D-penicillamine

botulinum toxin type A

interferon alfa

–

Use with caution

neuromuscular blocking drugs:

Intravenous lidocaine and large doses of other local anaesthetics (even given subcutaneously) can potentiate the effect of neuromuscular blocking drugs. However, in general, local anaesthesia is safe in myasthenia gravis

nondepolarising

Avoid if possible, or use with extreme caution (cause highly variable potentiation of neuromuscular blockade)

Avoid long-acting agents (eg pancuronium)

Reduce doses, according to disease severity and concurrent use of anticholinesterase inhibitors

Closely monitor neuromuscular function and consider a test dose

depolarising

Avoid if possible, due to variable response

A loss of acetylcholine receptors in myasthenia gravis may confer a degree of resistance to depolarising drugs

In contrast, cholinesterase inhibitors and vancomycin may potentiate the action of suxamethonium

halogenated inhalation anaesthetics

Myasthenic patients may be more sensitive to the relaxant effect of inhaled anaesthetics. Monitor neuromuscular function closely

antibiotics:

aminoglycosides

Use an alternative drug when possible. Tobramycin is probably the least toxic

fluoroquinolones

Use an alternative drug when possible

macrolides

Use an alternative drug when possible

quinine

Use an alternative drug when possible

iodinated radiographic contrast media

Use noncontrast imaging when possible and discuss with radiologist

Note: NB1: Case reports suggest several other drugs (eg beta blockers [including eye drops], verapamil, statins, lincosamide antibiotics) exacerbate myasthenia gravis symptoms. Rather than avoiding these drugs completely, consider their harms versus benefits before deciding whether to use them.