Abstract: Objective To discuss rat body weight, organ index and histopathological changes in long-term toxicity experiment of Kursi Kaknaq in SD rats. Methods A total of 120 healthy SD rats, half male and half female, were randomly divided into the control, low (0.32 g·kg^-1·d^-1), middle (1.6 g·kg^-1·d^-1) and high (3.2 g·kg^-1·d^-1) of Kursi Kaknaq. The drug was given orally, 6 days a week for 180 days, and the controls were given with 0.5% sodium carboxymethyl cellulose suspension. The body weight, organ index and histopathological changes were examined when those rats were treated 90 days, 180 days and stoped for 30 days. Results Compared with the control group, there was no significant difference in body weight and organ index changes of rats in each period (P >0.05). In the 3.2 g (crude drug)· kg^-1·d^-1 group, organs of rats did not show drug-induced obvious histopathological changes. There were also no obvious toxic target organs. Conclusion No obvious toxicity was observed in SD rats treated with Kursi Kaknaq at 0.32, 1.6, 3.2 g (crude drug)·kg^-1·d^-1 given orally for 180 days in rat body weight, organ index ,and no obvious toxic target organs in the dose of 3.2 g·kg^-1·d^-1 (equivalent to 50 times of the recommended adult clinical doses ). It indicated that this drug has no obvious toxicity.

Key words: Kursi Kaknaq, rat, chronic toxicity, body weight, organ index, histopathology