Effects of amitraz given by different routes on rats

Three-mo-old male Wistar rats were sprayed with 250, 500, 1000 and 2000 ppm amitraz 2 w apart or given single doses of 50, 100, or 250 mg/kg p.o, i.m. or i.p. No effects were observed in the amitraz-sprayed rats. Single doses of amitraz p.o, i.m. or i.p. was non-toxic at 50 mg/kg, toxic at 100 mg/kg and lethal at 250 mg/kg within 24 h of dosing. Survivors were killed 48 h post-dosing. Features of toxicity were depression, incoordination of movement, paresis of the limbs, hepatonephrotoxicity, muscular hemorrhage at site of injection and peritonitis following i.p. injection. These changes, accompanied by leucopenia, were correlated with alterations in serum AST and concentrations of serum constituents. Amitraz did not inhibit serum ChE activity.