Abstract: Objective To evaluate the chronic toxicity of Zhinao capsules to SD rats and to provide reference for safe clinical medications. Methods One hundred and sixty normal rats were randomly divided into four groups: the negative control group (pure water) and three-dosage groups of Zhinao capsules (6 400, 2 100 and 710 mg·kg^-1), with 40 rats in each. The rats were orally administrated with Zhinao capsules for 26 weeks. The health status, food consumption and body weight of rats were observed during the test. At 13 weeks, 26 weeks and after two weeks of recovery, 10, 20 and 10 rats in each group were dissected respectively before hematology, blood biochemistry, the organ-body ratio and histopathology were measured. Results Compared with the negative control group, the body weight of male rats in the high-dose group decreased from week 13 to week 21 (P < 0.05) but returned to normal at 26 weeks (P > 0.05). Compared with the negative control group, some hematological and blood biochemical indexes of rats in the medium and high dose groups were increased before they decreased (P < 0.05), but all were within the normal range. Compared with the negative control group, the male kidney/body ratio, the female liver/body ratio and the ovary/body ratio were increased in the high dose group after 26 weeks of administration (P < 0.05). There was no difference in the organ-body ratio between the three groups in the two weeks of recovery (P > 0.05), and no histopathological lesions of organs induced by drugs were observed either. Conclusion Long-term administration of Zhinao capsules is highly safety, and the NOAEL of Zhinao capsules is considered to be 6 400 mg·kg^-1, equal to 95 times the proposed clinical adult .

Key words: Zhinao capsules, chronic toxicity, safety, SD rats, dosages