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:
Hypersensitivity to naphazoline
Patients taking MAO inhibitors can experience a severe hypertensive crisis if given a sympathomimetic drug such as naphazoline HCl
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
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.
Extended use may cause rhinitis medicamentosa, a condition of rebound nasal congestion.
A possible association with stroke has been suggested.[2]
Chemistry[edit]
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
References[edit]
Jump up ^ Green, S. M. (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 0-7637-6572-4.
Jump up ^ 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.
Jump up ^ A. Sonn, U.S. Patent 2,161,938 (1939)
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:
Hypersensitivity to naphazoline
Patients taking MAO inhibitors can experience a severe hypertensive crisis if given a sympathomimetic drug such as naphazoline HCl
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
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.
Extended use may cause rhinitis medicamentosa, a condition of rebound nasal congestion.
A possible association with stroke has been suggested.[2]
Chemistry[edit]
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
References[edit]
Jump up ^ Green, S. M. (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 0-7637-6572-4.
Jump up ^ 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.
Jump up ^ A. Sonn, U.S. Patent 2,161,938 (1939)
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