May increase neuromuscular block w/ inhalational anesth eg, halothane, isoflurane & enflurane. Increased magnitude &/or duration w/ antibiotics, including aminoglycosides, polymyxins, spectinomycin, tetracyclines, lincomycin & clindamycin; antiarrhythmics (propranolol, Ca channel blockers, lidocaine, procainamide & quinidine); diuretics (furosemide & possibly mannitol, thiazides & acetazolamide); Mg sulfate; ketamine; lithium salts; ganglion blocking agents (trimetaphan, hexamethonium). May aggravate or unmask latent myasthenia gravis or induce myasthenic syndrome w/ antibiotics, β-blockers (propranolol, oxprenolol), antiarrhythmics (procainamide, quinidine), anti-rheumatics (chloroquine, D-penicillamine), trimetaphan, chlorpromazine, steroids, phenytoin & lithium. Onset is likely to be lengthened & shortened the duration block in patients receiving chronic anti-convulsant therapy. Prolonged & complex block w/ suxamethonium. May shorten duration & diminish magnitude w/ donepezil.