Developmental toxicity study of Aquacoat® ECD ethylcellulose aqueous dispersion administered orally to rats

A developmental rat toxicity study of Aquacoat® ECD was performed as part of a program to evaluate the safety of the product. Groups of 25 presumed-pregnant Charles River Sprague–Dawley CD rats received doses of 0, 903, 2709 and 4515 mg/kg/day (dry weight basis) of Aquacoat ECD administered undiluted once daily via oral gavage on days 6–15 of gestation. All surviving dams underwent caesarean sectioning on day 20 of gestation. Foetuses were weighed, sacrificed and subject to external, visceral and skeletal evaluations. No test material-related maternal deaths occurred; one high-dose female died on day 14 due to gavage error. The only treatment-related clinical sign noted among dams receiving 2709 mg/kg/day and greater was pale faeces which was attributed to the presence of the test material in the faeces. No statistically significant differences were noted among the measured maternal parameters. Foetal sex ratios and body weights were similar in all groups. The results of external and visceral foetal evaluations revealed no treatment-related alterations. The only statistically significant findings noted during the skeletal evaluation were increased litter incidences of incompletely ossified or wavy ribs noted among foetuses receiving 4515 mg/kg/day, and a significant increase in the litter incidence of thickened ribs at doses of 2709 and 4515 mg/kg/day. Given the nature of these findings and the lack of effects on any other parameter measured in this study, they were not considered adverse effects of treatment. Under the conditions of this study, the maternal and foetal no-observed-adverse-effect level (NOAEL) is in excess of 4515 mg/mg/day.