Research Area: Cardiovascular Disease Biological Activity: Naphazoline hydrochloride (Naphcon) is an ocular vasoconstrictor and imidazoline derivative sympathomimetic amine. Naphazoline constricts the vascular system of the conjunctiva. Naphazoline is presumed that this effect is due to direct stimulation action of the drug upon the alpha adrenergic receptors in the arterioles of the conjunctiva resulting in decreased conjunctival congestion. Naphazoline (Naphcon) belongs to the imidazoline class of sympathomimetics. [1][2]