Comparative evaluation of the neuromuscular blocking activity of three new aminoglycoside antibiotics in rats.

The effects of three aminoglycoside antibiotics on the rat isolated phrenic nerve-diaphragm preparation and on the sciatic nerve-gastrocnemius muscle preparation were investigated. Tobramycin, amikacin and ribostamycin produced dose-dependent neuromuscular blockade of the diaphragm twitches. Comparison of results showed that the neuromuscular blocking potency was as follows: tobramycin greater than amikacin greater than ribostamycin. The neuromuscular blockade produced gy these antibiotics was reversed by calcium chloride, whereas it was not influenced by neostigmine methylsulfate. Furthermore, the neuromuscular blocking potency in vitro of these three aminoglycosides was paralleled by their activity in vivo on the sciatic nerve-gastrocnemius muscle preparation.