A number of drugs may cause a worsening of clinical findings in patients with myasthenia gravis (MG). The authors are from Columbia Asia Hospital, Baptist Hospital, K.S. Hegde Medical College and Dr B.R. Ambedkar Medical College in Bangalore, India.
The mechanism varies. Some of the drugs (chloroquine, corticosteroids) are associated with a myopathy. Penicillamine can induce an MG-like syndrome. Other drugs compete at the neuromuscular junction.
Penicillamine is associated with drug-induced MG, with development of anti-AChR antibodies.
Other drugs:
(1) chloroquine
(2) corticosteroids (prednisone)
(3) antibiotics (aminoglycosides, polymyxins, ciprofloxacin, erythromycin, ampicillin)
(4) beta-adrenergic receptor blocking agents (propranolol, timolol)
(5) lithium
(6) magnesium
(7) procainamide
(8) verapamil
(9) quinidine
(10) anticholinergic drugs
(11) neuromuscular blocking agents (vecuronium, curare)
Diagnosis:
(1) The person is diagnosed with myasthenia gravis.
(2) The person is taking one of the implicated drugs.
(3) The patient improves after the drug is discontinued. The time period for reversal may take months.
