[Safety evaluation of micronomicin IV. Acute toxicity in rats, rabbits and dogs after drip intravenous infusion].

Micronomicin (MCR) is a new aminoglycoside antibiotic produced by Micromonospora sagamiensis var. nonreducans which was isolated from soil collected at Sagamihara City by Nara et al. This antibiotic shows a close similarity to gentamicin C components in physical and chemical properties. The antibacterial activity of MCR is broad-spectrum and almost equal to that of gentamicin C complex. MCR exhibits particularly high activity against Pseudomonas, Proteus, Klebsiella pneumoniae, Serratia, etc, as well as against some Pseudomonas aeruginosa strains resistant to gentamicin C1a. Toxicological studies of MCR were carried out for safety evaluation as follows: Studies were carried out to assess acute toxicity, when administered in 1 hour by drip intravenous infusion to Wistar rats, Japanese White rabbits and Beagle dogs. The results of the studies are summarised as follows: There was no difference on acute toxicity between drip intravenous infusion (d.i.v.) and intramuscular injection (i.m.) in rats. However, acute toxicity of d.i.v. was less than that of bolus intravenous administration (i.v.) in rats. Acute toxicity of d.i.v. was stronger than that of i.m. in dogs when administered in rats. Acute toxicity varied with species, and it was ranked in rabbits not equal to dogs greater than rats. There was no difference on symptoms between d.i.v. and i.m.