Which of the following drugs is useful as a nasal decongestant due to its α1 agonist activity?

Oxymetazoline is effective as a nasal decongestant primarily because of its action as an α1 adrenergic agonist. The stimulation of α1 receptors on smooth muscle in nasal blood vessels leads to vasoconstriction, resulting in decreased blood flow to the nasal mucosa. This vasoconstriction reduces swelling and congestion, providing relief from nasal obstruction often associated with conditions like the common cold or allergic rhinitis.

Other medications listed in the choices, such as albuterol and salmeterol, primarily act on β2 adrenergic receptors, which are more involved in bronchodilation rather than causing vasoconstriction or addressing nasal congestion. Ephedrine, while it has some α1 agonist activity and can act as a decongestant, is not typically the first choice compared to oxymetazoline due to its systemic side effects and less specific action on the nasal passages. Thus, oxymetazoline stands out as the more direct and effective option for nasal decongestion through α1 agonist activity.