Abstract: AIM: To investigate the effects of eri-geron injection on liver microsomal cytochrome P450 (CYP450) system in mice .METHODS: Mice were divided into control group (CG) , positive control group, normal-dosage group (NG) and high-dosage group (HG) .The mice of control group were given sa-line only and the mice of positive control group were given Phenobarbital sodium injection (PBN) at 80 mg/kg by peritoneal injection (i .p.) , once daily for seven days.The remaining two groups were i .p.with 10 mg/kg (normal-dosage group) and 30 mg/kg (high-dosage group) erigeron injection, respectively, once daily for two weeks.Then the total content and activi-ties of CYP450 of mice were determined by spectropho-tometer .RESULTS: The study showed that the cont-ent of CYP450 and protein in mice of normal-dosage group and high-dosage group were higher than those in control group, except liver indexes.In terms of the eri-geron injection effects on Erythromycin-N-demethylase and aminopyrine-N-demethylase, the normal-dosage group and high-dosage group can decrease the activity of Erythromycin-N-demethylase (P <0.01) , but had no effect on aminopyrine-N-demethylase (P >0.05) . Phenobarbital sodium can increase the levels of liver indexes, the content of CYP450 and protein(P < 0.05) , Erythromycin-N-demethylase and aminopyrine-N-demethylase (P <0.01) .CONCLUSION: The erigeron injection had no effect on the liver indexes and the levels of aminopyrine N-demethylase in mice. However, the content of CYP450 and protein, and the levels of Erythromycin N-demethylase were affected. The erigeron injection may be an inhibitive agent to CYP3A.

Key words: erigeron injection, mice, liver micro-some, cytochrome P450