Naphazoline is a rapid acting sympathomimetic vasoconstrictor of occular artierioles. It acts to decrease congestion of the conjunctiva and is found in many over-the-counter eye drops.
Indication
Naphazoline is primarily indicated in conditions like Corneal vascularity, Hyperaemia, Itching, Nasal congestion, and can also be given in adjunctive therapy as an alternative drug of choice in Sinusitis
Pharmacology
Naphazoline is a direct acting sympathomimetic adrenergic alpha-agonist used to induce systemic vasoconstriction, thereby decreasing nasal congestion and inducing constriction around the conjunctiva. The sympathomimetic action of Naphazoline constricts the smaller arterioles of the nasal passages, producing a decongesting effect. Naphazoline ophthalmic causes constriction of blood vessels in the eyes. It also decreases itching and irritation of the eyes. aphazoline constricts the vascular system of the conjunctiva. It 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 belongs to the imidazoline class of sympathomimetics.
Toxicity
Extended usage of Naphazoline can result in decreased effectiveness or a build up of tolerance against the drug. The number of receptors decreases, and when the administration of the drug is ceased, chronic congestion can occur; this is called rhinitis medicamentosa, commonly referred to as rebound congestion. Moreover long-term overdosing can cause degenerative changes in nasal mucous membranes that pose another health problem.
