This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hypeension, Arrhythmias, Dyslipidemia, Subject name: Pharmacology
Which of the following drugs can result in cyanide poisoning? 
Select and explain. 
A. Sodium Nitroprusside, B. Amyl nitrite, C. Hydroxycobalamin, D. Sodium thiosulphate
A: Sodium Nitroprusside
Answer: A: Sodium Nitroprusside 
Explanation: Rapid high dose infusion of sodium nitroprusside may result in cyanide poisoning. Mechanism of action of Sodium nitroprusside is binding with oxyhemoglobin in the circulation and release nitric oxide, cyanide, methaemoglobin results inincrease of cGMP Amyl nitrite induces methemoglobinemia which binds cyanide to form cyanmethemoglobin and thiosulphate hastens its conversion to less toxic thiocyanate. Amyl nitrite and sodium thiosulphate are present in commercial cyanide antidote kit. Hydroxocobalamin conves cyanide to non-toxic cyanocobalamin. Note Sodium nitroprusside- DOC for Malignant hypeension