Objective: To study the dose and time dependent hepatotoxicity and pathological change induced by Radix et Rhizoma Sophorae Tonkinensis (RRST) in mice. Method: After 14 days observation

the medial lethal dose (LD50) of RRST decoction with oral administration in mice was calculated. In addition

the liver weight/body weight index was measured

and pathological change of liver under microscope was observed. Result: The LD50 value of RRST of batch A (No. 081012) was 31.935 g (crude drug) /kg

with the 95% confidence level between 30.509~33.506 g (crude drug)·kg-1;that of batch B (No. 0904295) was 16.39 g (crude drug)·kg-1

with the 95% confidence level between 14.426~18.38 g (crude drug)·kg-1. The time dependent study indicated that the enlargement of the liver and the liver weight/body weight indexes of the mice 6 hour after oral administration with decoction A at the dosage of 30g (crude drug)·kg-1

or decoction B at the dosage of 12.4 g (crude drug)·kg-1

were obviously increased when compared with that of the normal control mice. The hepatic damage was most serious in 24 hours. The dose dependent study indicated that oral administration with decoction A at the dosage of 16.4

10

3.2

and decoction B at the dosage of 12.4

10.8

10

9.2

8

7.2 g (crude drug) /kg caused increase of liver weight/body weight indexes

and dose dependent damage of the liver tissue. Conclusion: One-time oral administration with large dose of decoction of RRST may induce acute hepatotoxicity and even death in mice in a time and dose dependent manner.