Effect on blood and plasma cyanide levels and on methaemoglobin levels of cyanide administered with and without previous protection using PAPP.

Hydrogen cyanide was administered intravenously at doses of 0.67 or 1.34 mg kg-1 to beagle bitches after protection with oral p-aminopropiophenone (0.5 mg kg-1). Hydrogen cyanide was also administered to unprotected bitches at the lower level (0.67 mg kg-1) only. PAPP protection caused sequestration of cyanide inside the red cells. In the case of the lower dose of cyanide this resulted in a lower plasma cyanide in protected than unprotected bitches. In the case of the higher dose it resulted in survival, despite 1.34 mg kg-1 being a known lethal dose. It is concluded that prior administration of PAPP ameliorated the effects of cyanide poisoning.