Naphazoline
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. 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 (eg cannabis induces corneal vasodilation). 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: Ophthalmic drug administration. Known side-effect: Pharmacology. Pharmacodynamics. Naphazoline is a mixed α- and α-adrenergic receptor agonist. Chemistry. The non-hydrochloride form of Naphazoline has the molecular formula CHN 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.