Developmental toxicity evaluation of rats dosed orally or cutaneously with octoxynol-9.

Pregnant CD rats were dosed cutaneously (530, 1600 or 4270 mg kg-1 day-1) or fed diets containing octoxynol-9 (70 or 340 mg kg-1 day-1) during the major period of organogenesis. Monitors for maternal toxicity included clinical observations, body weight, organ weight and food consumption. Fetuses were evaluated for body weight and for external, visceral and skeletal abnormalities. Maternal effects were noted in dams dosed cutaneously with 4270 mg kg-1 day-1 octoxynol-9, and included excoriation, exfoliation/desquamation in the area of treated skin, urine stains, perinasal encrustation and audible respiration. In addition, maternal weight gains were reduced during the dosing period. Octoxynol-9, dosed orally or cutaneously to gravid rats, had no effect on pregnancy performance but increased the incidences of a number of developmental abnormalities in the offspring. Most notable was the induction of supernumerary ribs arising from the lumbar and cervical regions. Other skeletal abnormalities included decreased incidences of poorly ossified supraoccipital and hyoid bones and zygomatic arches, suggesting an enhanced ossification in the neck and head regions. Increased incidences of two fetal visceral abnormalities, displaced tests in dams dosed orally with 340 mg kg-1 day-1 and atelectasis in dams dosed cutaneously with 1600 or 4270 mg kg-1 day-1 were also observed.