Naphalon

Uses

Acute and chronic non-infectious conjunctivitis, nonspecific conjunctival irritation; also after successful treatment of bacterial and viral conjunctivitis. Irrigation of the tear ducts.

Naphalon is also used to associated treatment for these conditions: Bacterial Conjunctivitis, Blepharoconjunctivitis, Conjunctivitis, Conjunctivitis allergic, Dacryocystitis, Dacryostenosis, Dermatitis, Eczematous of the Eyelid, Eye Pain, Eye redness, Iritis, Lacrimation, Nasal Allergies, Nasal Congestion, Noninfective conjunctivitis, Otitis Media (OM), Photophobia, Foreign body sensation in eye, Ocular bacterial infections, Ocular vasoconstriction

How Naphalon works

Naphazoline is a vasoconstrictor that functions by stimulating alpha adrenergic receptors in arterioles leading to decreased congestion at the site of administration.

Naphazoline causes the release of norepinephrine in sympathetic nerves. Norepinephrine binds to alpha adrenergic receptors and causes vasoconstriction. Naphazoline is also a mild beta adrenergic receptor agonist, which can cause rebound vasodilation after the alpha adrenergic stimulation has ended. Naphazoline's release of norepinephrine also triggers a negative feedback loop which decreases production of norepinephrine, which can lead to rhinitis medicamentosa after long term use when naphazoline is stopped.

Dosage

Naphalon dosage

Adults: 1 drop in the conjunctival sac, three to 4 times per day.

Children: Naphazoline nitrate and Zinc sulphate drops has not been studied in children. Generally, in children the dosage of vasoconstrictors should be low and selected with caution.

Side Effects

Mydriasis and a slight increase of intraocular pressure in isolated cases. A slight and transient burning sensation may occur after instillation, which does not affect the success of the treatment. Long term use may result in reactive redness of the eye (rebound effect).

In very rare cases systemic cardiovascular effects, such as hypertension and arrhythmia, may occur. Nonspecific fatigue has been observed in some patients.

Toxicity

In high doses or when ingested, naphazoline can lead to central nervous system depression (which can progress to coma and death), hypothermia, bradycardia, and death. This effect is especially pronounced in children under 6 years.

Long term use of naphazoline can lead to rhinitis medicamentosa once naphazoline is stopped. This condition is a result of norepinephrine release by naphazoline triggering a negative feedback loop.

Safety and effectiveness in children under 12 has not been established. Studies in elderly patients have yet to be performed. Risk in pregnancy, breast feeding, and on overall fertility have not been established, though pregnant and breast feeding patients should consider the risk and benefit before starting naphazoline treatment.

Precaution

Uncontrolled use of Naphazoline & Zinc over extended periods of time should be avoided. If no improvement is seen after 2 days, treatment should be discontinued and other therapeutic measures should be considered. If ocular discomfort or visual disturbance occurs during Naphazoline & Zinc treatment, the therapy must be discontinued. Caution is indicated in patients with predisposition to glaucoma and in patients suffering from hypertension, cardiovascular diseases, pheochromocytoma, aneurysm, hyperglycemia, and hyperthyroidism.

Interaction

Naphazoline containing products should not be administered during treatment with MAO-blockers nor during 10 days after discontinuation of such treatment. The effects of Naphazoline may be increased by concomitant use of tricyclic antidepressants.

Volume of Distribution

Distribution data for naphazoline are scarce but imidazoline compounds are distributed throughout the body, and can cross the blood-brain barrier.

Elimination Route

Absorption data for naphazoline are scarce but imidazoline compounds in general are weakly basic and lipophilic, with high bioavailability from the gastrointestinal tract.

Half Life

Half life has not been determined but effects last for 4 to 8 hours. Other imidazoline compounds have half lives varying from 2 to 12 hours.

Clearance

Clearance data for naphazoline is unavailable.

Elimination Route

Imidazoline compounds undergo some hepatic metabolism but a large fraction of the dose may be excreted unchanged in the urine. Urinary excretion is higher with more acidic urine.

Pregnancy & Breastfeeding use

Use in pregnancy: There are neither controlled animal studies nor studies in pregnant women available.

Use in lactation: The effects of Naphazoline & Zinc treatment during lactation have not been investigated.

Contraindication

Hypersensitivity to zinc sulphate, Naphazoline and other ingredients. Naphazoline & Zinc is contraindicated in patients suffering from narrow-angle glaucoma, dry eye and especially keratoconjunctivits sicca Sjogren's syndrome. Naphazoline & Zinc must not be used in infants.

Innovators Monograph

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