This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
In case of cyanide poisoning, antidote of amyl nitrate is given. This is an example of: 
Select and explain. 
A. Receptor antagonism, B. Chemical antagonism, C. Physical antagonism, D. Physiological antagonism
B: Chemical antagonism
Answer: B: Chemical antagonism 
Explanation: Ans. (b) Chemical antagonismRef: Vasudevan Biochemistry, 8th ed. P 321* Chemical: A type of antagonism where a drug counters the effect of another by simple chemical reaction/neutralization (not binding to the receptor).* Physiological: Two drugs act on two different types of receptor and antagonize action of each other.* Competitive: Both drugs bind to same receptor.