Comparison of acute toxicity of two preparations of norcantharidin in mice

Objective: To compare the acute toxicity of common injection and sustained-release preparation of norcantharidin for mice so as to identify the attenuation of the sustained-release preparation of norcantharidin. Methods: The poloxamer 407 was used as a sustained-release vehicle for topical administration of norcantharidin, and the acute toxicity of mice treated with common injection and sustained-release preparation of norcantharidin was observed. The median lethal dose (LD50) was calculated by Bliss software. Results: The symptoms of mice were similar between the two groups, but the appearance of symptoms in norcantharidin/poloxamer 407 group was 4 hours later than that in norcantharidin group. The LD50 of norcantharidin administered through vein injection was 12.6 mg/kg. The LD50 of norcantharidin/poloxamer 407 administered through intraperitoneal injection, intrahepatic injection and intramuscular injection were 19.9, 19.1 and 20.9 mg/kg, respectively, and the LD50 of the common preparation were 13.0, 13.1 and 15.1 mg/kg, respectively. Conclusion: The norcantharidin/poloxamer 407 is less toxic than the equivalent dose of norcantharidin, mainly because norcantharidin/poloxamer 407 may release norcantharidin sustainedly, thus reducing norcantharidin concentration in blood.