Naphazoline

Naphazoline

Systematic (IUPAC) name
2-(naphthalen-1-ylmethyl)-4,5-dihydro-1H-imidazole
Clinical data
Trade names	Naphcon-a
AHFS/Drugs.com	monograph
Pregnancy cat.	?
Legal status	?
Routes	Topical
Identifiers
CAS number	835-31-4 N
ATC code	R01AA08
PubChem	CID 4436
DrugBank	DB06711
ChemSpider	4283 Y
UNII	H231GF11BV Y
KEGG	D08253 Y
ChEMBL	CHEMBL761 Y
Chemical data
Formula	C14H14N2
Mol. mass	210.274
SMILES	eMolecules & PubChem
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) Y Key:CNIIGCLFLJGOGP-UHFFFAOYSA-N Y
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

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 arrythmia 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

Naphazoline, 2-(1-naphthylmethyl)-2-imidazoline, is 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

• A. Sonn, U.S. Patent 2,161,938 (1939).

References