[Muscle-relaxant effects of intravenously administered micronomicin]

Pharmacological effects, mainly on its muscle-relaxant of micronomicin (MCR) were studied. Intravenous infusion of MCR at a dose of 20 mg/kg/hour did not influence on both respiration rate and cardiovascular functions in anesthetized rabbits. When MCR was injected to anesthetized rabbit at an intravenous dose of 100 mg/kg, a respiratory arrest followed by a cardiac arrest was observed. This effect was antagonized by either treatment with CaCl2 or artificial respiration. In slant test, MCR at a dose of 100 mg/kg (i.v.) in mice induced muscle relaxation. This effect was weakened by slowing the injection speed of the drug. Intravenous injection of MCR potentiated the lethality induced by either d-tubocurarine or succinylcholine. Intravenous injection of MCR influenced on neither pentobarbital sodium-, ethyl ether-, nor halothane-induced anesthesia in mice. From these results, intravenous infusion of MCR at a dose of 20 mg/kg/hour that is considered as 5 approximately 10 times of clinical dose (120 approximately 240 mg/day) did not influence on both respiration and cardiovascular functions.