Amyl nitrate is used as an antidote in which poisoning?: (A) Arsenic poisoning, (B) Hydrocyanide poisoning, (C) Lead poisoning, (D) Yellow poisoning
Answer is B. Ans. is 'b' i.e., Hydrocyanide poisoning * Amyl nitrite is used as an antidote in poisoning of hydrocyanic acid (cyanide).* Nitrates generate methaemoglobin which has high affinity for cyanide and forms cyanmethaemoglobin.* Cyanmethaemoglobin may again dissociate to release cyanide, therefore, sodium thiosulfate is given to form sod. thiocyanate which is poorly dissociable and is excreted in urine.