Introduction
Opcon-A is a combination ophthalmic solution containing naphazoline hydrochloride (a vasoconstrictor) and pheniramine maleate (an antihistamine). It is classified as an over-the-counter ophthalmic decongestant/antihistamine combination medication primarily used for temporary relief of ocular redness and itching associated with minor eye irritations and allergic conjunctivitis.
Mechanism of Action
Naphazoline hydrochloride acts as a direct-acting sympathomimetic amine that stimulates alpha-adrenergic receptors in the arterioles of the conjunctiva, producing vasoconstriction and resulting in decreased conjunctival congestion and whitening of the sclera. Pheniramine maleate is a histamine H1-receptor antagonist that competitively inhibits histamine binding at receptor sites, thereby reducing allergic symptoms including itching, redness, and watering of the eyes.The combination provides both symptomatic relief of allergic manifestations and reduction of ocular redness through complementary mechanisms.
Indications
- Temporary relief of redness of the eye due to minor irritations
- Relief of ocular itching associated with allergic conjunctivitis
- Symptomatic treatment of minor eye irritations caused by pollen, ragweed, grass, animal dander, and hay fever
Dosage and Administration
Standard dosing: Instill 1-2 drops in the affected eye(s) up to four times daily as needed Administration:- Wash hands before use
- Avoid contaminating dropper tip
- Do not touch eye or any surface with dropper tip
- Tilt head back, pull down lower eyelid to form pouch
- Instill drops into conjunctival sac
- Close eyes gently for 1-2 minutes after instillation
- Apply gentle pressure to lacrimal sac for 1 minute to minimize systemic absorption
- Wait at least 10 minutes before inserting contact lenses
- Pediatric use: Not recommended for children under 6 years without medical supervision
- Geriatric use: No dosage adjustment required
- Hepatic/renal impairment: No specific recommendations available
Pharmacokinetics
Absorption: Minimal systemic absorption following ocular administration; however, nasolacrimal drainage may lead to some systemic exposure Distribution: Primarily local ocular distribution; minimal systemic distribution if absorbed Metabolism: Hepatic metabolism if systemically absorbed Elimination: Renal elimination of metabolites if systemically absorbed Half-life: Not well characterized due to primarily local actionContraindications
- Hypersensitivity to any component of the formulation
- Narrow-angle glaucoma
- Patients wearing soft contact lenses (solution contains benzalkonium chloride preservative)
- Concomitant use with monoamine oxidase inhibitors (MAOIs)
- Children under 6 years of age
Warnings and Precautions
- Rebound hyperemia: Prolonged use (beyond 72 hours) may cause rebound redness and conjunctival congestion
- Systemic effects: May be absorbed systemically and cause cardiovascular effects including hypertension, arrhythmias, and tachycardia
- Mydriasis: May cause pupillary dilation, which could precipitate angle-closure glaucoma in susceptible individuals
- Corneal problems: Discontinue use and consult physician if eye pain, vision changes, or persistent redness occurs
- Diabetes: Use with caution in patients with diabetes mellitus
- Hypertension: Use with caution in patients with hypertension, cardiovascular disease, or hyperthyroidism
- Pregnancy: Category C - Use only if potential benefit justifies potential risk to fetus
- Nursing mothers: Exercise caution when administering to nursing women
Drug Interactions
- MAO inhibitors: May potentiate pressor effects (contraindicated)
- Tricyclic antidepressants: May potentiate pressor effects
- Beta-blockers: Potential for paradoxical hypertension
- Other sympathomimetic drugs: Additive cardiovascular effects
- Antihypertensive medications: May antagonize hypotensive effects
Adverse Effects
Common (>1%):- Transient stinging/burning upon instillation
- Blurred vision
- Pupillary dilation
- Headache
- Dryness of the eye
- Cardiovascular effects (hypertension, palpitations, tachycardia)
- CNS effects (dizziness, nervousness, insomnia)
- Rebound conjunctival hyperemia
- Angle-closure glaucoma
- Allergic reactions
Monitoring Parameters
- Ocular symptoms (redness, itching) before and after administration
- Visual acuity changes
- Intraocular pressure in susceptible individuals
- Signs of rebound hyperemia with prolonged use
- Cardiovascular parameters in patients with pre-existing conditions
- Signs of hypersensitivity reactions
Patient Education
- Use only as directed - do not exceed recommended dosage or duration
- Remove contact lenses before instillation and wait at least 10 minutes before reinserting
- Do not use if solution changes color or becomes cloudy
- Discard bottle 30 days after opening
- Do not share medication with others
- Seek medical attention if symptoms persist beyond 72 hours, worsen, or if eye pain, vision changes, or persistent redness occurs
- Inform healthcare providers of all medications being taken
- Store at room temperature, protected from light
- Keep out of reach of children
References
1. FDA OTC Monograph for Ophthalmic Drug Products. 21 CFR Part 349. 2. Bartlett JD, Jaanus SD. Clinical Ocular Pharmacology. 5th ed. Butterworth-Heinemann; 2008. 3. Opcon-A [package insert]. Alcon Laboratories, Inc.; 2021. 4. Abelson MB, Schaefer K. Conjunctivitis of allergic origin: clinical presentation and differential diagnosis. Surv Ophthalmol. 1993;38 Suppl:105-114. 5. Bielory L, Delgado L, Katelaris CH, et al. ICON: Diagnosis and management of allergic conjunctivitis. Ann Allergy Asthma Immunol. 2020;124(2):118-134. 6. PharmD Assist: Ophthalmic Drug Handbook. 4th ed. American Society of Health-System Pharmacists; 2019.