Phenylephrine is a drug that affects alpha-1 adrenergic receptors. It is used in nasal sprays to promote vasoconstriction of blood vessels in the nasal mucous membranes. This increased blood vessel vasoconstriction decreases blood flow to the nasal mucosa, thus helping to reduce congestion during seasonal allergies.
This drug is acting as an agonist / antagonist.
Explain how you determined this: