Abstract:ABSTRACT:Objective To compare the curative effect of tribendimidine (TBD) oral administration at different courses of treatment against Trichinella spirails encapsulated larvae in striated muscle in mice. Methods Forty 8 week old BALB/c mice were randomly divided equally into 5 groups infected orally each mouse with 50 Trichinella spiralis encapsulated larvae. Twenty ninth day after infection, TBD was each orally administered to 5 groups with 300mg/ (kg?d) at different courses of treatment (lasted for 0, 2, 4, 6 or 8 d), respectively. The drug untoward reactions for mice were observed. Mice were sacrificed on the day 7 after drug withdrawal. The encapsulated larvae in diaphragmatic muscle, jugomaxillary muscle, pectoral muscle and gastrocnemius muscle were observed with pellet method and the total, survival and dead worms were counted. Another forty 8 week old BALB/c mice were randomly divided equally into 5 groups, infected orally each mouse with 50 Trichinella spiralis encapsulated larvae in diaphragmatic muscle of mice that orally administered TBD 300mg/(kg?d) at different courses of treatment. On the day 29 after infection, encapsulated larvae in diaphragmatic muscle were observed and counted with pellet method. Results During the experimental session, health statuses of mice were fine, not detected drug adverse reaction. The total worm burden and survival worms were downtrend and dead worms were raise tendency in four muscles as the course of treatment increased. Compared with the 0 d courses of treatment group, the total and survival worms in diaphragmatic muscle, jugomaxillary muscle and gastrocnemius muscle of 2 d and over 2 d courses of treatment were significantly decreased (P<0.05, P<0.01), the total worm in pectoral muscle of 2 d and over 2 d courses of treatment groups were was significantly decreased (P<0.05, P<0.01). As the courses of treatment were increase, the death rate of encapsulated larvae were raise tendency in four muscles, 6 d course of treatment group为96.16%、98.06%、99.13% and 98.56%(P<0.01),8 d course of treatment group为99.62%-100%(P<0.01)。The authenticity infection for curative effect indicated that infection rates 6 d (37.5%) and 8 d courses of treatment groups (12.5%) were significantly lower than 0 d (100%) and 2 d courses of treatment groups (100%) (P<0.01). Mean worm burden and Mean worm reduction (%) of mice in 2 d and over 2 d courses of treatment were significantly decreased than that of control group (P<0.01). Conclusion Oral administered TBD 300mg/kg?d to mice for 6 d or 8 d did not detected adverse drug reaction, and could effectively kill encapsulated larvae and was a suitable course of treatment against encapsulated larva stage of the parasite.