Reproductive studies of NY-198 in rats. I. Fertility study.

Lomefloxacin (NY-198), a new antibacterial agent, was administered daily by gavage to groups of 22 male and 22 female rats at dosages of 30, 100 or 300 mg/kg/day. Males were dosed for 71 days before pairing and then until termination, and females were dosed for 15 days before pairing, throughout mating and until Day 7 of gestation. Females were killed on Day 20 of gestation for examination of their uterine contents. Males were killed after approximately 14 weeks treatment and their reproductive organs were weighed and retained. At 300 mg/kg/day the majority of animals showed increased salivation, water intake was slightly increased throughout the treatment period in males and before pairing in females whereas food intake showed a slight, transient reduction during the first few days of treatment in both sexes. Body weight gain of males was marginally depressed during the first week of treatment, but no other signs of reaction to treatment were observed. At 30 and 100 mg/kg/day some animals exhibited increased salivation after being dosed. At all dosages, NY-198 was without adverse effects upon mating performance and fertility, or upon survival, growth and development in utero. On the basis of the above results it is considered that the no effect level with respect to reproduction and breeding performance of treated F0 animals and the in utero development of the foetuses was 300 mg/kg/day. A dosage of 100 mg/kg/day was considered to be the no effect level for somatic changes in the F0 animals, and even at the highest dosage of 300 mg/kg/day only slight effects were recorded on the F0 animals.