What is the mechanism of action of phenylephrine in the treatment of nasal congestion?

Phenylephrine is an agonist of α1-adrenoceptors. Nasal decongestant action is mediated by activation of α1-adrenoceptors in the arterioles of the nasal mucosa. This causes vasoconstriction, which leads to decreased edema and increased drainage of the sinus cavities.

Does phenylephrine decrease contractility?

Phenylephrine is a selective α1-adrenergic receptor agonist that increases blood pressure mainly by increasing systemic vascular resistance, without an associated increase in myocardial contractility.

What is the mechanism of action of nasal decongestants?

The mechanism by which decongestants produce their action is activation of postjunctional a-adrenergic receptors found on precapillary and postcapillary blood vessels of the nasal mucosa.

What receptors does phenylephrine stimulate?

Phenylephrine produces its local and systemic actions by acting on α1-adrenergic receptors peripheral vascular smooth muscle. Stimulation of the α1-adrenergic receptors results in contraction arteriolar smooth muscle in the periphery.

Is phenylephrine an agonist or antagonist?

Phenylephrine is primarily an alpha-1 adrenergic receptor agonist with minimal to no beta-adrenergic activity; therefore, it is ideal for elevating mean arterial pressure.

Is phenylephrine a vasoconstrictor?

Phenylephrine is a pure vasoconstrictor and is not recommended for empiric use, although niche uses for phenylephrine include (1) difficulty raising mean arterial pressure in the presence of high cardiac output as well as (2) serious tachyarrhythmias induced by norepinephrine (not usually an issue).

Does phenylephrine increase preload or afterload?

As a pure α-agonist, phenylephrine is conventionally considered to solely induce arterial vasoconstriction and thus increase cardiac afterload but not cardiac preload.

How does phenylephrine decrease cardiac output?

Conclusion: impact of phenylephrine on cardiac output is related to preload dependency. When the heart is preload independent, phenylephrine boluses induce on average a decrease in cardiac output. When the heart is preload dependent, phenylephrine boluses induce on average an increase in cardiac output.

Why do decongestants cause vasoconstriction?

Nasal decongestants are vasoconstrictors that belong to the pharmacologic class sympathomimetic amines. They exert their primary action by activating alpha-adrenergic receptors on blood vessels of the nasal mucosa. This results in vasoconstriction, which decreases blood flow through the nasal mucosa and shrinks tissue.

How do sympathomimetics relieve nasal congestion?

Pharmacologic therapy. Decongestants treat sinus and nasal congestion. They are adrenergic agonists (sympathomimetics) that constrict blood vessels, thereby decreasing sinusoid vessel engorgement and mucosal edema.

What is the action of phenylephrine?

Phenylephrine is in a class of medications called nasal decongestants. It works by reducing swelling of the blood vessels in the nasal passages.

Does phenylephrine constrict blood vessels?

Phenylephrine works by directly stimulating alpha-1 adrenergic receptors in the arteries causing vasoconstriction (narrowing of the blood vessels). This reduces nasal congestion by preventing fluid from draining from the blood vessels into the tissues lining the nasal passages.