Oxymetazoline

Oxymetazoline is a selective alpha-1 agonist and partial alpha-2 agonist topical decongestant, used in the form of Oxymetazoline hydrochloride, in products such as Nasivion, Vicks Sinex and Afrin. Oxymetazoline is generally available as a nasal spray. It causes down-regulation of alpha-2 receptors, and therefore becomes less effective after a few doses. If overused it can cause a "rebound congestion" (rhinitis medicamentosa) where the mucosal surface of the sinuses are damaged due to ischemia, become swollen, and therefore become congested after the drug wears off. As a result, a user can develop physiological tolerance to the drug, manifested by prolonged nasal congestion without continued use of the medication. (See the discussion of the effect of benzalkonium chloride, a common additive to oxymetazoline nasal sprays, in the article Rhinitis medicamentosa.)

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The medication has sympathomimetic properties, and thus constricts the blood vessels of the nose and sinuses via activation of alpha-2 adrenergic receptors, an in turn causes a decrease in interstitial fluid accumulation (nasal edema). It is frequently used by anaesthesiologists to reduce nasal bleeding during nasal endotracheal intubations. This drug, like most sympathomimetic amines, has adrenergic properties due to its mode of action. However, since the application is topical, it has practically no CNS stimulation as of the systemic application of decongestants such as pseudoephedrine.

Since no clinical data on exposed pregnancies are available with oxymetazoline, the safe use of oxymetazoline during pregnancy has not been established.

If accidentally ingested, standard methods to remove unabsorbed drugs should be considered. There is no specific antidote for oxymetazoline, although its pharmacological effects may be reversed by alpha adrenergic antagonists such as phentolamine. In children, oxymetazoline may produce profound central nervous system depression due to stimulation of central alpha-2 receptors and imidazoline receptors, much like clonidine.

Oxymetazoline HCl 0.025% is also the active ingredient in Visine L.R. Long-Lasting Redness Relief eye drops.