Increased neuromuscular blockade by inhalation anesth eg, halothane, isoflurane, enflurane. Increased magnitude &/or duration of nondepolarizing neuromuscular blockade w/ aminoglycosides, polymyxins, spectinomycin, tetracyclines, lincomycin, clindamycin; propranolol, Ca-channel blockers, lignocaine, procainamide, quinidine; furosemide, mannitol, thiazide diuretics, acetazolamide; Mg sulfate, ketamine, lithium salts; trimetaphan, hexamethonium. May aggravate or unmask latent myasthenia gravis w/ β-blockers, antiarrhythmics, antirheumatics, trimetaphan, chlorpromazine, steroids, phenytoin, lithium. Lengthened onset & shortened duration of nondepolarizing neuromuscular block by chronic anticonvulsant therapy.