Other antibiotics, such as aminoglycosides, can increase the potential of polymyxins for nephrotoxicity and neurotoxicity and they should be co-administered with the greatest caution with polymyxins. The concurrent use of polymyxins with a curariform muscle relaxant and other neurotoxic drugs such as ether, tubocurarine, succinylcholine, gallamine, decamethonium, and sodium citrate should be used with great caution also, since these agents may potentiate the development of neuromuscular blockade. Co-administration of sodium cephalothin and colistin may enhance the development of nephrotoxicity, so this medication should be avoided.
In addition, antimicrobial agents with known neurotoxic effect, such as aminoglycosides, should generally be in such instance, close monitoring of the patients received these antibiotics is mandatory. Experimental studies showed that application of polymyxins in combination with glutamic acid to a peripheral nerve could cause transganglionic degenerative atrophy.