[Neuromuscular blocking properties of arbekacin, astromicin, isepamicin and netilmicin in the rabbit]

The neuromuscular blocking properties of aminoglycoside group of antibiotics arbekacin sulfate (ABK), astromicin sulfate (ASTM), isepamicin sulfate (ISP), netilmicin sulfate (NTL) and d-tubocurarine were studied in 30 rabbits anesthetized with pentobarbital. The left gastrocnemius tendon was cut and secured to a force-displacement transducer. The left tibial nerve was directly stimulated by electrodes with supramaximal square waves of 0.1 msec duration at a frequency of 0.1 Hz. The resultant force of twitch tension was recorded. The intravenous administration of ABK 60-100 mg/kg, ASTM 160-320 mg/kg, ISP 320-480 mg/kg or NTL 20-40 mg/kg resulted in dose-dependent decreases in twitch tensions. The ED50 values of 4 antibiotics were NTL = 30.2 mg/kg (4.2 x 10(-2) mmol/kg) < ABK = 78.3 mg/kg (1.4 x 10(-1) mmol/kg) < ASTM = 215.2 mg/kg (3.6 x 10(-1) mmol/kg) < ISP = 359.7 mg/kg (6.3 x 10(-1) mmol/kg), respectively. These antibiotics-induced blockades were antagonized by calcium or by neostigmine. Although the relative neuromuscular blocking potencies of 4 antibiotics equipotent to d-tubocurarine on the basis of therapeutic doses in man were below 0.6 mg, it may be concluded that the potential clinical hazard lies in the sequence of administration of the aminoglycoside group of antibiotics.