Circulation,respiration, and blood homeostasis in cyanide-poisoned dogs after treatment with 4-dimethylaminophenol or cobalt compounds

The effects of intravenously injected 4-dimethylaminophenol-HCl (DMAP), Co₂EDTA, and Co(histidine)₂ on the survival rate and several physiological parameters were studied on dogs after acute intravenous poisoning with the double lethal dose of potassium cyanide.All dogs survived when the antidotes were administered 1 min after poisoning. When the therapy began 4 min after poisoning more dogs were rescued in the DMAP group than in the cobalt groups. DMAP, Co₂EDTA, and Co(histidine)₂ restored circulation and respiration of the surviving animals in a similar manner.The increase in the plasma concentrations of glucose and lactate was much higher in the Co₂EDTA group than in the DMAP group. The injection of Co₂EDTA produced a sharp rise in the lactate-to-pyruvate ratio. The lactate-to-pyruvate ratio stayed unchanged for some 15 min after injection of DMAP before also rising. The total dose of KCN (4 mg/kg) was bound to the ferrihemoglobin formed by DMAP. The arterial pO₂ increase, caused by liberation of oxygen from oxyhemoglobin during the formation of ferrihemoglobin, was less when the cyanide could act on the tissues for a longer period of time before the therapy with DMAP began.DMAP is more appropriate for the therapy of cyanide poisoning than Co₂EDTA, since the latter adds its inhibitory effects on the metablism to those of cyanide.