Neuromuscular blocking action may be enhanced w/ antibiotics, cyclosporin, ketamine, lithium, local anaesth (eg, lidocaine), Mg salts, quinidine, procainamide, verapamil. Actions may be potentiated w/ general anaesth. Decreased neuromuscular blocking effects w/ theophyllines, & may increase w/ thiazide diuretics. Carbamazepine, hydantoins (eg, phenytoin).