JEE Main 2020 · 4 September · evening · Single correct · +4 / −1
The mechanism of action of ''Terfenadine'' (Seldane) is :
- (a) Activates the histamine receptor
- (b) Helps in the secretion of histamine
- (c) Inhibits the secretion of histamine
- (d) Inhibits the action of histamine receptor
Answer and solution
Answer (d) Inhibits the action of histamine receptor
Solution
Chemistry ma’am · 4 steps
Terfenadine is an antihistamine: histamine is still released, but its receptor is blocked.
- What histamine does. In an allergy, the body releases histamine. Histamine binds to its receptors and causes sneezing, itching, a runny nose and rashes.
- Where terfenadine acts. Terfenadine (Seldane) is an antihistamine. It competes with histamine for the binding site on the receptor, so histamine cannot attach and produce its effect.
- Check each option. Terfenadine does not switch the receptor on, so (a) is wrong. It does not change how much histamine is released, so (b) and (c) are wrong. It only stops the receptor from responding.
- So. Terfenadine inhibits the action of the histamine receptor, which is option (d).
The idea to keep. Antihistamines like terfenadine, brompheniramine and cetirizine act at the receptor. Histamine is still released, but it has nowhere to bind, so it cannot cause the allergy symptoms.
Answer from the NTA final answer key. Solution by PrepWiser.