OBJECTIVE To evaluate the safety and the effect on growth and development of SD rats of Xiao Du San(XDS) on juvenile SD rats through a 13-week repeated oral administration toxicity test in juvenile SD rats.

METHODS One hundred and sixty juvenile SD rats(the initial age of administration was 21 d) were randomly divided into four groups: vehicle control group(1% CMC-Na), low dose, medium dose, high dose group(1250, 2500, 5000 mg·kg⁻¹·d⁻¹); there were 40 rats in each group, with an equal number of males and females. The rats were orally administered once a day for 13 weeks, followed a 4 weeks recovery period. The animals were dissected in batches at weeks 6, 13, and the end of recovery period. Test items included body weight, food intake, bone measurement, sexual development indicators, behavioral indicators, hematology, blood biochemistry, coagulation indicators, etc.

RESULT XDS 5000 mg·kg⁻¹ and 2500 mg·kg⁻¹ caused an increase in relative liver weight, liver cell hypertrophy, and an increase in total bilirubin levels in male rats. XDS 5000 mg·kg⁻¹ could cause hypertrophy of renal tubular epithelial cells and an increase in the relative weight of the kidneys in male rats. There was no significant effect of XDS on the growth and development of juvenile SD rats.

CONCLUSION Under the conditions of this experiment, the no observed adverse effect level of juvenile rats in repeated oral administration toxicity test for 13 weeks is 1250 mg·kg⁻¹.