Naphazoline

Naphazoline
Clinical data
Trade names	Clear Eyes, Cleari, Naphcon-A, Rohto
AHFS/Drugs.com	Monograph
Routes of; administration	Ophthalmic drug administration, nasal administration
ATC code	R01AA08 (WHO) S01GA01 (WHO);
Legal status
Legal status	In general: Over-the-counter (OTC);
Identifiers
	IUPAC name 2-(naphthalen-1-ylmethyl)-4,5-dihydro-1H-imidazole;
CAS Number	835-31-4 ;
PubChem CID	4436;
IUPHAR/BPS	5509;
DrugBank	DB06711 ;
ChemSpider	4283 ;
UNII	H231GF11BV;
KEGG	D08253 ;
ChEMBL	ChEMBL761 ;
CompTox Dashboard (EPA)	DTXSID3048449 ;
ECHA InfoCard	100.011.492
Chemical and physical data
Formula	C14H14N2
Molar mass	210.274 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES N\1=C(\NCC/1)Cc2cccc3c2cccc3;
	InChI InChI=1S/C14H14N2/c1-2-7-13-11(4-1)5-3-6-12(13)10-14-15-8-9-16-14/h1-7H,8-10H2,(H,15,16) ; Key:CNIIGCLFLJGOGP-UHFFFAOYSA-N ;
	(what is this?)

Naphazoline is a medicine used as a decongestant, and a vasoconstrictor added to eye drops to relieve red eye. It has a rapid action in reducing swelling when applied to mucous membrane. It is a sympathomimetic agent with marked alpha adrenergic activity that acts on alpha-receptors in the arterioles of the conjunctiva to produce constriction, resulting in decreased congestion.

It was patented in 1934 and came into medical use in 1942.^[1]

Medical uses[]

Red eyes can be treated with naphazoline.

Nasal administration[]

Nasal decongestant.^[2]

Ophthalmic drug administration[]

Eye drops (brand names Clear Eyes, and Cleari) narrowing swollen blood vessels (ophthalmic arteries, and ophthalmic veins) to relieve red eye.^[2]

Temporary red eye can safely be treated when the cause of the redness is established (eg cannabis induces corneal vasodilation^[3]). However, long-term use is not recommended without knowing the underlying condition.

Side effects[]

A few warnings and contraindications that apply to all naphazoline-containing substances intended for medicinal use are:

Hypersensitivity to naphazoline
Use in infants and children can result in central nervous system depression, leading to coma and marked reduction in body temperature
Should be used with caution in patients with severe cardiovascular disease including cardiac arrhythmia and in patients with diabetes, especially those with a tendency toward diabetic ketoacidosis
A possible association with stroke has been suggested.^[4]

Nasal administration[]

Extended use may cause rhinitis medicamentosa, a condition of rebound nasal congestion.

Ophthalmic drug administration[]

Known side-effect:^[5]^[6]

Stinging
Discomfort
Irritation
Increased red eyes
Blurred vision
Mydriasis
Punctate keratitis
Lacrimation (tears)
Increased intraocular pressure

Contraindications[]

Patients taking MAO inhibitors can experience a severe hypertensive crisis if given a sympathomimetic drug such as naphazoline HCl
Drug interactions can occur with anaesthetics that sensitize the myocardium to sympathomimetics (e.g. cyclopropane or halothane cautiously)
Exercise caution when applying prior to use of phenylephrine.

Pharmacology[]

Pharmacodynamics[]

Naphazoline is a mixed α₁- and α₂-adrenergic receptor agonist.^[2]

Chemistry[]

The non-hydrochloride form of Naphazoline has the molecular formula C₁₄H₁₄N₂ and a molar mass of 210.28 g/mol. The HCl salt form has a molar mass of 246.73 g/mol.

Society and culture[]

Brand names[]

It is an active ingredient in several over-the-counter eye drop formulations including Clear Eyes, Rohto, Eucool, and Naphcon-A.^[7]

References[]

^ Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 552. ISBN 9783527607495.
^ ^a ^b ^c Hosten LO, Snyder C (2020). "Over-the-Counter Ocular Decongestants in the United States - Mechanisms of Action and Clinical Utility for Management of Ocular Redness". Clinical Optometry. 12: 95–105. doi:10.2147/OPTO.S259398. PMC 7399465. PMID 32801982.
^ Yazulla, S (September 2008). "Endocannabinoids in the retina: from marijuana to neuroprotection". Progress in retinal and eye research. 27 (5): 501–26. doi:10.1016/j.preteyeres.2008.07.002. PMC 2584875. PMID 18725316.
^ Zavala JA, Pereira ER, Zétola VH, Teive HA, Nóvak EM, Werneck LC (September 2004). "Hemorrhagic stroke after naphazoline exposition: case report". Arquivos de Neuro-Psiquiatria. 62 (3B): 889–91. doi:10.1590/S0004-282X2004000500030. PMID 15476091.
^ "Naphazoline - FDA prescribing information, side effects and uses". Drugs.com.
^ "naphazoline ophthalmic (eye): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD". www.webmd.com.
^ Green SM (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 978-0-7637-6572-9.

[Fis2006-1] Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 552. ISBN 9783527607495.

[pmid32801982-2] Hosten LO, Snyder C (2020). "Over-the-Counter Ocular Decongestants in the United States - Mechanisms of Action and Clinical Utility for Management of Ocular Redness". Clinical Optometry. 12: 95–105. doi:10.2147/OPTO.S259398. PMC 7399465. PMID 32801982.

[3] Yazulla, S (September 2008). "Endocannabinoids in the retina: from marijuana to neuroprotection". Progress in retinal and eye research. 27 (5): 501–26. doi:10.1016/j.preteyeres.2008.07.002. PMC 2584875. PMID 18725316.

[pmid15476091-4] Zavala JA, Pereira ER, Zétola VH, Teive HA, Nóvak EM, Werneck LC (September 2004). "Hemorrhagic stroke after naphazoline exposition: case report". Arquivos de Neuro-Psiquiatria. 62 (3B): 889–91. doi:10.1590/S0004-282X2004000500030. PMID 15476091.

[5] "Naphazoline - FDA prescribing information, side effects and uses". Drugs.com.

[6] "naphazoline ophthalmic (eye): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD". www.webmd.com.

[7] Green SM (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 978-0-7637-6572-9.

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