Reproductive studies of NY-198 in rats. II. Teratology study

Lomefloxacin (NY-198), a new antibacterial agent, was administered daily by gavage to groups of 32 pregnant female rats of the CD strain at dosages of 30, 100 or 300 mg/kg/day from Day 7 to Day 17 of gestation. Twenty-one females in each group were killed on Day 20 of gestation for examination of their uterine contents. Eleven females in each group were allowed to deliver their litters and the offspring were examined for growth and functional development. At the highest dosage (300 mg/kg/day), there was a small reduction in maternal weight gain and a transient reduction in food intake during the treatment period. Foetal and placental weights were markedly reduced. However, survival, growth and development of F1 offspring were unaffected and, with the possible exception of a slight reduction in F2 foetal weight, their reproductive performance was unimpaired. At the intermediate level (100 mg/kg/day), maternal body weight gain and food intake during the treatment period were slightly reduced but, with this exception, the performance of F0 females and of the F1 generation was essentially similar to that of the vehicle controls. At the lowest dosage (30 mg/kg/day), no adverse effects were recorded on either the F0 females or the F1 generation. On the basis of the above results 30 mg/kg/day was considered to be the no effect level for the F0 females treated during gestation while 100 mg/kg/day administered during gestation to F0 females had no effect upon performance of the F1 generation.