[Safety evaluation of micronomicin. III. Teratogenicity studies in rats]

Micronomicin (MCR) is a new aminoglycoside antibiotic produced by Micromonospora sagamiensis var. nonreducans which was isolated from soil collected at Sagamihara by Nara et al. The purified antibiotic showed a close similarity to gentamicin C complex 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. and high activity against some Pseudomonas aeruginosa strains resistant to gentamicin C1a. Teratogenicity 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. 1. Fetal malformation attributable to MCR was not observed at any dose. 2. Suppression of maternal weight gain was observed at the dose levels of 50 mg/kg and over. 3. There was no adverse effect on new borns at any dose.