Objective To find out the acute and long-term toxicities of purified CV-CTX from Chinese cobra venom in mice,Methods Fifty
mice were divided into five groups,each given different dose of CV-CTX iv, The death rate was estimated within 7 day.Five dogs were given different doses of CV-CTX iv after anaesthetized with sodium pentobarbital.The blood pressure,ECG,respiratory rate were recorded at 10￣30 min interval.One hundred and sixty rats (same number for both sexes)were divided into four groups.One
group received ip 0.9% NaCl 20 ml /kg·d-1 as control,the another three groups received ip CV-CTX 250,500,1000μg/kg·d-1 respectively for 40 days continuously.Results The LD50 and 95% confidence limits of CV-CTX in mice was 1158. 7(1070￣1254. 6)μg/kg. After administration the mice decreased their spontaneous movements and some died within 6 hrs. In dogs received iv CVCTX 100 μg/kg every hour for five times no change in blood pressue.Dose which larger than 500 μg/kg caused cardiac arrhythmia and heart arrest.The
liver and renal functions as well as biochemical assays of blood were in normal range in all rats after CV-CTX ip 40 days; Pathomorphological examination showed that 4 and 3 rats in the high dose group appeared liver focal necrosis and dispersive lung haemorrhage respectively. But in median dose group only mild cloudy swelling in liver cells and focal haemorrhage in lung were observed.All the pathological changes disappeared when CV-CTX had discontinued after 30 days,Conclusion The toxicity of long-term CV-CTX administration appeared only in the liver and lung,but these toxic changes were reversible.It is suggested that CV-CTX may be prepared as a drug for clinical use.