[Safety evaluation of micronomicin IX. Perinatal and postnatal study by intravenous injection in rats].

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. Perinatal and postnatal studies of MCR in rats were carried out by intravenous injection for safety evaluation (Dose; 25, 50 mg/kg and 75 mg/kg). The results of studies are as follows. There was no adverse effect on delivery and nursing ability in dams at any dose. There was no adverse effect at any dose on postnatal development of offspring, such as weight gain, postnatal differentiation, spontaneous motor activity, learning, sexual maturation and reproductive performance. Renal toxicity was observed at dose of 75 mg/kg in autopsy of dams after treatment.