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 membranes. 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.

Medical uses

Nasal administration

Nasal decongestant.

Ophthalmic drug administration

Eye drops (brand names Clear Eyes, and Cleari) narrowing swollen blood vessels (ophthalmic arteries, and ophthalmic veins) to relieve red eye. Temporary red eye can safely be treated when the cause of the redness is established (e.g. cannabis induced corneal vasodilation). However, continuous use is not recommended without knowing an underlying condition.

Side effects

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

Nasal administration

Ophthalmic drug administration

Known side-effect:

Contraindications

Pharmacology

Naphazoline is a mixed α1- and α2-adrenergic receptor agonist.

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

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

Illicit use

The nasal or ophthalmic form of naphazoline has been abused by heroin or cocaine drug addicts. It's used as CNS stimulant and vasoconstrictor to enhance primary drug effects.