Objective: To compare the toxicities and organ injuries of cantharidin and norcantharidin in mice. Method: Balb/c mice were treated with cantharidin or norcantharidin at different doses for two weeks to determine their median lethal dose (LD50) by the probability unit regression analysis method. Other mice were treated with 1/2 LD50 of the respective drugs for 2 weeks. At the end of the treatment

tissue samples from livers

intestines

kidneys and bladders were collected for pathological analyses. Result: LD50 of cantharidin and norcanditharidin were 2.045 and 20.966 mg·kg-1. Norcantharidin caused significant increases in alanine aminotransferase (ALT) and rea nitrogen (BUN). Norcantharidin caused inflammatory cell infiltration and sponge-like change in liver

and injuries in glomeruli and renal tubules. Cantharidin led to increases in intestinal lymph nodes and lobulation in the intestine

vascular

bladder and mucosa inflammations. Conclusion: Treatments with 1/2 LD50 dose of norcantharidin and cantharidin led to distinct organ/tissue-specific injuries in mice. Norcantharidin caused severe injuries in liver and kidney

while cantharidin led to severer injuries in intestinal and bladder than norcantharidin.