The efficiency of aquocobalamine as an antidote in cyanide poisoning when given alone or combined with sodium thiosulfate.

The antidotal activities of aquocobalamineacetates and sodium thiosulfate were tested in guinea pigs and cats. The animals were attached to artificial respirators throughout the experiment and were poisoned with a continuous infusion of sodium cyanide solution (4.1 muMol/kg.min NaCN). The rate of action of each antidote was determined from the time taken for the HCN exhalation to drop below the level of 100 nMol/kg.min in quinea pigs, and to values below 25 nMol/kg.min in cats; the detoxifying capacity of each antidote was determined from the time taken for the HCN exhalation to rise above the said values and the time interval for normal function of heart activity to be restored. Aquobalamine was characterized by its rapid rate of reaction in both the animal species; its detoxifying capacity showed, however, according to our expectations, variations corresponding to the applied doses. The combination of the antidotes aquocobalamine (100 mg/kg) and thiosulfate (500 mg/kg) proved to possess high rate of reaction and a large detoxifying capacity in guinea pigs. Similar results were obtained in cats with antidote doses of 200 mg/kg aquocobalamine combined with 500 mg/kg thiosulfate. The slow rate of reaction and large detoxifying capacity of thiosulfate were confirmed in our experiments. It combination with aquocobalamine showed no undesirable change in its antidotal action providing a time interval of 1 min was maintained between the 2 injections.