Oxymetazoline is a selective ?1 adrenergic receptor agonist and ?2 adrenergic receptor partial agonist. It is a topical decongestant, used in the form of oxymetazoline hydrochloride. It was developed from xylometazoline at E. Merck Darmstadt by Fruhstorfer in 1961. Oxymetazoline is generally available as a nasal spray.
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Medical uses
Oxymetazoline is available over-the-counter as a topical decongestant in the form of oxymetazoline hydrochloride in nasal sprays such as Otrivin, Afrin, Operil, Dristan, Dimetapp, Oxyspray, Facimin, Nasivin, Nostrilla, Sudafed OM, Vicks Sinex, Zicam, SinuFrin, and Mucinex Full Force.
Due to its vasoconstricting properties, oxymetazoline is also used to treat nose bleeds and eye redness due to minor irritation (marketed as Visine L.R. in the form of eye drops).
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Side effects and special considerations
Rebound congestion
It is recommended that oxymetazoline not be used for more than three days, as rebound congestion, or rhinitis medicamentosa, may occur. Patients who continue to use oxymetazoline beyond this point may become dependent on the medication to relieve their chronic congestion.
Effects of benzalkonium chloride
Some studies have found that benzalkonium chloride, a common additive to oxymetazoline nasal sprays, may damage nasal epithelia and exacerbate rhinitis medicamentosa. However, the majority of studies find benzalkonium chloride to be a safe preservative.
Use in pregnancy
The Food and Drug Administration places oxymetazoline in category C, indicating risk to the fetus cannot be ruled out. While it has been shown that a single dose does not significantly alter either maternal or fetal circulation, this subject has not been studied extensively enough to draw reliable conclusions.
Overdose
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 ? adrenergic antagonists such as phentolamine. In the event of a possibly life-threatening overdose (such as a hypertensive crisis), benzodiazepines should be considered to decrease the likelihood of seizures and convulsions, as well as reduce anxiety and to lower blood pressure. In children, oxymetazoline may produce profound central nervous system depression due to stimulation of central ?2 receptors and imidazoline receptors, much like clonidine.
Pharmacology
Mechanism of action
Oxymetazoline is a sympathomimetic that selectively agonizes ?1 and, partially, ?2 adrenergic receptors. Since vascular beds widely express ?1 receptors, the action of oxymetazoline results in vasoconstriction. In addition, the local application of the drug also results in vasoconstriction due to its action on endothelial postsynaptic ?2 receptors; systemic application of ?2 agonists, in contrast, causes vasodilation because of centrally-mediated inhibition of sympathetic tone via presynaptic ?2 receptors. Vasoconstriction of vessels results in relief of nasal congestion in two ways: first, it increases the diameter of the airway lumen; second, it reduces fluid exudation from postcapillary venules. It can reduce nasal airway resistance (NAR) up to 35.7% and nasal mucosal blood flow up to 50%.
Pharmacokinetics
Imidazolines are sympathomimetic agents, with primary effects on ? adrenergic receptors and little if any effect on ? adrenergic receptors. Oxymetazoline is readily absorbed orally. Effects on ? receptors from systemically absorbed oxymetazoline hydrochloride may persist for up to 7 hours after a single dose. The elimination half-life in humans is 5-8 hours. It is excreted unchanged both by the kidneys (30%) and in feces (10%).
History
The oxymetazoline brand Afrin was first sold as a prescription medication in 1966. After finding substantial early success as a prescription medication, it became available as an over-the-counter drug in 1975. Schering-Plough did not engage in heavy advertising until 1986. From the late 1980s to mid 1990s, Afrin featured in many notable television advertisements. Some of these commercials showed men, women, and children using other brands of nasal sprays, and then standing upside down or hanging upside down from playground equipment to prevent their nasal spray from dripping out. This was juxtaposed with Afrin users having no problems.
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Brand names
Brand names include Afrin, Drixine, Dristan, Nasivin, Nasivion, Nezeril, Nostrilla, Logicin, Vicks Sinex, Visine L.R., Sudafed OM, Zicam, SinuFrin and Mucinex Sinus-Max.
Source of the article : Wikipedia
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