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Naphazoline Structural Formulae.png
Systematic (IUPAC) name
Clinical data
Trade names Naphcon-a
AHFS/ monograph
Legal status ?
Routes Topical
CAS number 835-31-4 N
ATC code R01AA08 S01GA01
PubChem CID 4436
DrugBank DB06711
ChemSpider 4283 YesY
KEGG D08253 YesY
Chemical data
Formula C14H14N2 
Mol. mass 210.274
 N (what is this?)  (verify)

Naphazoline (in the hydrochloride form) is the common name for 2-(1-naphthylmethyl)-2-imidazoline hydrochloride. It is a sympathomimetic agent with marked alpha adrenergic activity. It is a vasoconstrictor with a rapid action in reducing swelling when applied to mucous membrane. It acts on alpha-receptors in the arterioles of the conjunctiva to produce constriction, resulting in decreased congestion. It is an active ingredient in several over-the-counter formulations including Clear Eyes and Naphcon eye drops.[1]

It has the molecular formula C14H14N2.HCl and a molecular weight of 246.73 g/mol.

Warnings and contraindications[edit]

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

A possible association with stroke has been suggested.[2]


Naphazoline can be synthesized from (1-naphthyl)acetonitrile, which upon reaction with ethanol transforms into iminoester, and undergoes further heterocyclization into the desired imidazoline derivative upon reaction with ethylene diamine.[3]

Naphazoline synthesis.png


  1. ^ Green, S. M. (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 0-7637-6572-4. 
  2. ^ Zavala, J. A.; Pereira, E. R.; Zétola, V. H.; Teive, H. A.; Nóvak, E. M.; Werneck, L. C. (2004). "Hemorrhagic stroke after naphazoline exposition: case report". Arquivos de Neuro-Psiquiatrica 62 (3B): 889–891. doi:10.1590/S0004-282X2004000500030. PMID 15476091. 
  3. ^ A. Sonn, U.S. Patent 2,161,938 (1939)