Efficacy of digoxin specific Fab fragments (Digibind) in the treatment of toad venom poisoning

Chan Su, a traditional Chinese medication, and Love Stone, a topical aphrodisiac, are both made from dried venom of the toad bufo bufo gargarizans and contain bufalin, cinobufotalin, cinobufagin, and other cardioactive steroids of the bufadienolide class. Deaths have occurred following ingestion of these products and the clinical course resembles digoxin toxicity. The purpose of this study was to determine the efficacy of digoxin specific Fab fragments in treating Chan Su poisoning. An ethanolic extract was prepared from Chan Su. Digoxin specific Fab fragments were reconstituted in normal saline to a concentration of 80 mg/ml. An approximate LD90 dose was determined in preliminary experiments. Mice were then randomly divided into a treatment group of 15 mice and a control group of 30 mice. The treatment group was pretreated with 20 ml/kg of digoxin specific Fab fragment solution by intraperitoneal injection at t = 0, followed by 10 ml/kg of digoxin specific Fab fragments intraperitoneal at t = 30 min. The control group was pretreated with equal volumes of intraperitoneal normal saline at the same times. Immediately following the 30 min injection, both groups were given the estimated LD90 dose of Chan Su extract by subcutaneous injection. An endpoint of survival at 6 h was chosen after preliminary results showed that all deaths occurred in the first 4 h. All 30 of the control mice had seizures followed by death compared to 11 seizures and 7deaths in the 15 treatment mice. These results were statistically significant by Fisher's exact test (p = 0.00003 for mortality and p = 0.009 for seizures). Digoxin specific Fab fragments are effective in the treatment of Chan Su poisoning in mice and may be effective for poisoning by other cardioactive steroids of the bufadienolide class.