Objective： To evaluate the acute and sub-chronic toxicity of intravenously administered tetrandrine（TET） in female BALB/c mice. Methods： The median lethal dose（LD_（50）） of intravenously administered TET was calculated in mice using Dixon＇s up-and-down method. In the acute toxicity study, mice were intravenously administered with TET at a single dose of 20, 100, 180, 260 and 340 mg/kg, respectively and were evaluated at 14 days after administration. In the sub-acute toxicity study, mice were intravenously administered various doses of TET（30, 90 and 150 mg/kg） each day for 14 consecutive days. Clinical symptoms, mortality, body weight, serum biochemistry, organ weight and histopathology were examined at the end of the experiment, as well as after a 1-week recovery period. Result： LD_（50） was found to be 444.67±35.76 mg/kg. In the acute toxicity study, no statistically significant differences in body weight, blood biochemistry, or organ histology were observed between the administration and control groups when mice were intravenously administered with single dose at 20, 100, 180, 260 and 340 mg/kg of TET（P〉0.05）. In the sub-acute toxicity study, no significant changes in body weight, biochemistry and organ histology were observed with up to 90 mg/kg of TET compared with the control group（P〉0.05）, however, in the 150 mg/kg administered group, TET induced transient toxicity to liver, lungs and kidneys, but withdrawal of TET can lead to reversal of the pathological conditions. Conclusions： The overall findings of this study indicate that TET is relatively non-toxic from a single dose of 20, 100, 180, 260 or 340 mg/kg, and that up to 90 mg/kg daily for 14 consecutive days can be considered a safe application dose.
