A simple way to remember the drugs that should be used with caution in myasthenia gravis is the “14 A’s”:4-7
| ACTH and corticosteroids | prednisone |
| Analgesics | narcotics |
| Anesthetics, local | cocaine, procaine, lidocaine, bupivacaine, prilocaine |
| Antacids or laxatives containing magnesium | Maalox, Mylanta |
| Antiarrhythmics | quinidine, lidocaine, procainamide |
| Antibiotics | aminoglycosides, quinolones, telithromycin, azithromycin, erythromycin, clindamycin, ampicillin, imipenem, vancomycin, metronidazole |
| Anticonvulsants | phenytoin |
| Antihypertensives | beta-blockers, calcium channel blockers |
| Antimanics | lithium salts |
| Antipsychotics | chlorpromazine |
| Antirheumatic | chloroquine |
| Arthritis agents | penicillamine-induced myasthenia gravis |
| All neuromuscular blocking agents | |
| Antimalarials | chloroquine, hydroxychloroquine |
Table 1. Medications to be used with caution in myasthenia gravis.3-7
| Drug | Onset (from initiation) | Resolution |
| Prednisone | 1 to 2 weeks | 1 to 20 days |
| Streptomycin | 15 min to 1.5 hours | <24 hours |
| Iodinated contrast media | minutes | 2 to 48 hours |
| Botulinum toxin | minutes | 2 weeks |
| Procainamide | 2 days to 2 weeks | 12 hours to 10 days |
| Erythromycin | During infusion; 30 minutes after dose | 2 to 3 days |
| Ciprofloxacin | 4 hours to 2 days | Several days |
| Ampicillin | 12 hours to several days | 48 hours |
| Quinidine | 72 hours | 48 hours |
| Lithium | 10 days to 3 months | 3 to 4 days |
| Timolol, acebutolol, propranolol, oxprenolol, practolol | 24 hours to several days | 24 hours to 8 weeks |
| Penicillamine | 8 months | 6 to 10 months |
| Chloroquine | 1 week – 3.5 years | 5 days to 14 weeks |
| Phenytoin | 4 to 6 years | 2 to 3 months |
| Imipenem-cilastin | 2 days | 48 hours |
| Verapamil | 4 days | 2 weeks |
| Trimethaphan | 2 to 17 hours | |
| Procaine | 7 minutes | |
| Lidocaine | 7 minutes | |
| Aprotinin | during infusion | 10 to 90 minutes |
| Levocarnitine | 3 weeks | resolved after edrophonium |
http://dig.pharm.uic.edu/faq/myasthenia.aspx
