Question

Decongestants elicit their effect by which of the following mechanisms?

A. Selectively binding to peripheral H1 receptors
B. Not selectively binding to central and peripheral H1 receptors
C. Anesthetizing stretch receptors in the respiratory passages
D. Vasoconstriction of small blood vessels of the nasal membranes

Answer 1

Decongestants, through the activation of α₁-adrenergic receptors, cause vasoconstriction in the nasal blood vessels, reducing nasal congestion.

Step-by-step explanation:

Decongestants elicit their effect by vasoconstriction of small blood vessels of the nasal membranes. This action is due to the activation of α₁-adrenergic receptors by sympathomimetic drugs such as phenylephrine, which is commonly found in decongestants. This leads to the constriction of the blood vessels, thereby decreasing swelling and congestion in the nasal passages. Phenylephrine, as an α₁-adrenergic agonist, stimulates these receptors which results in the alleviation of congestion.