Abstract: 　Objective To detect the in vitro effect of the traditional Chinese medicine on the tachyzoites of Toxoplasma gondii. Methods Supernatant (1.5 ml) of different doses of the traditional Chinese medicine (Changqing capsule) was collected by normal saline immersion and 2.5×10⁴ Toxoplasma gondii tachyzoites were added in each paste well for 8 hours. Spiramycin, pyrimethamine and azithromycin in different doses were used as controls. Normal saline was used as negative control. Mice were inoculated with drug-treated tachyzoites intraperitoneally or intragastrically. The normal mice were subcultured after 8 days for 3 generations. Results The incident number of the infected mice was significantly different among groups with different drugs and doses: 2/60, 16/60, 10/60 and 10/60 in the groups of Changqing capsule, spiramycin, pyrimethamine and azithromycin respectively (P<0.05). No mice were found incident in groups of high and medium dose Changqing capsule while 2 out of 20 found sick in the low dose group (P<0.05). The subculture observation showed that 2 and 1 mice in the first generation of the low dose Changqing capsule group inoculated intraperitoneally and intragastrically were found infected respectively. 2 mice of the second generation in low dose spiramycin group and 1 mouse of the third generation in low dose pyrimethamine group were also found infected. Conclusion The in vitro killing effect of the Changqing capsule on the tachyzoites of Toxoplasma gondii is better than the current clinical drugs and shows a positive correlation with the dosages.

Key words: Changqing capsule, Toxoplasma gondii, In vitro effect