Question

During a serious allergic response, referred to as anaphylaxis, massive quantities of histamine are released, which causes a profound vasodilation that leads to large quantities of fluid filling the mucous membranes of the sinuses to close them, and leading to pronounced bronchoconstriction, reducing the ability to breathe. If unchecked this can lead to death. The emergency treatment for anaphylactic reactions is adrenaline, which will cause vasoconstriction in the mucous membranes and bronchodilation. What type of antagonist/antagonism does this represent? Select one:

a. competitive

b. chemical

c. pharmacokinetic

d. irreversible

e. physiological

Answer 1

Answer is option e.PHYSIOLOGICAL antagonism

Explanation:

Physiological antagonism ,also known as functional antagonism means there is opposite effects of two drugs on same function.That is two drugs acts on different receptors and antagonise action of each other.Here,histamine acts on histamine receptors and causes bronchoconstriction where as adrenaline acts on adrenergic receptors and cause opposite of it,bronchodilation.

Chemical antagonism means one drug counteracts the effect of another by simple chemical reaction or neutralisation(not binding to receptor).for eg;calcium sodium edetate forms insoluble complex with lead and arsenic.

Pharmacological antagonism can be competetive or non competetive.competetive antagonism can be reversible(antagonist bind to same receptor as agonist,and increase in concentration of agonist can reverse the antagonistic effect) and irreversible(bind to same receptor by covalent bond,cannot be reversed by increasing concentration).