Ophthalmic and Otic Disorders Pharmacology

Ophthalmic anti-infectives are pharmacological agents used to treat ocular infections and can be classified based on their action as either bacteriostatic (inhibiting growth) or bactericidal (killing bacteria).
Pharmacokinetics: These medications generally penetrate only the ocular fluid and tissues. There is minimal systemic absorption associated with these topical applications.
Precautions: Providers must use caution because these agents can trigger hypersensitivity reactions.

General ADR: The most common adverse reaction to ophthalmic anti-infectives is local irritation.
Super Infection: Prolonged use of these medications can lead to a super infection.
Bacitracin: Specifically known to cause blurred vision.
Aminoglycosides: Use can lead to localized ocular toxicity.
Fluoroquinolones: These may cause a white crystalline precipitate to form in the superficial portion of the cornea.
Reference Materials: Students are directed to study the following in their textbook: - Table $26-1$ : Lists ophthalmic anti-infectives, drug interactions, possible effects, and clinical implications. - Table $26-3$ : Discusses indications, forms, doses, and specific comments regarding each anti-infective ophthalmic medication.

Chlamydia Conjunctivitis in Newborns: - Shortly after birth, newborns typically receive Erythromycin eye ointment in both eyes to prevent Chlamydial conjunctivitis, which can lead to blindness. - If a newborn develops the infection, it is treated with systemic Erythromycin.
Bacterial Conjunctivitis: - Presentation: Symptoms include erythema, purulent discharge, itching, burning, and matted eyelashes (often referred to as "mad eyelashes"). - Demographics: While it can affect any individual of any age, it is more common in children between the ages of $3$ months and $8$ years. - Treatment: Typically managed with topical ophthalmic anti-infective medications.
Blepharitis: - Defined as acute or chronic inflammation of the eyelash follicles and the meibomian glands of the eyelids. - Treatment Protocol: Instruct the patient to scrub eyelashes with a gentle "no-tear" soap to clear follicles and glands. Treatment may also include Erythromycin ophthalmic ointment.
Hordeolums (Styes): - These are treated with antibiotic eye drops or ointments.
Viral Conjunctivitis: - Anti-infectives may be used if indicated; however, if Herpes is suspected, the patient must be referred immediately to an ophthalmologist.

Administration Techniques: - Prevent contamination by not touching the eye dropper to the eye. - Wash hands thoroughly both before and after administration. - Proper instruction on how to instill drops or ointment.
Lifestyle and Hygiene Management: - Do not share towels. - Avoid using eye makeup while the infection is being treated. - Clear purulent discharge using a wet cotton ball or a warm washcloth. - Apply warm compresses to the affected eye.

Mast Cell Stabilizers: These limit hypersensitivity reactions by inhibiting the degranulation of sensitized mast cells. They are typically used to treat vernal conjunctivitis.
Antihistamines: These work by blocking the Histamine $1$ ( $H1$ ) receptors. They are typically used to treat allergic conjunctivitis.
Precautions: - Can cause hypersensitivity reactions. - Products containing Benzalkonium chloride can affect soft contact lenses. Patients wearing contacts must be informed.
Common ADRs: - Stinging and burning upon instillation (most common). - Blurred vision, discomfort, or tearing.
Drug Interactions: Mast cell stabilizers and ocular antihistamines typically have no known drug interactions.

Classes: Available as Ophthalmic NSAIDs and Ophthalmic Corticosteroid agents.
Ocular Corticosteroids Specialist Referral: Any patient requiring ocular corticosteroids must be referred to an ophthalmologist due to severe risks.
Naphazoline (Nefazoline): An anti-inflammatory ocular agent that may precipitate narrow-angle glaucoma.
Risks of Ocular Corticosteroids: - Glaucoma (elevated intraocular pressure, optic nerve damage). - Loss of visual acuity and visual field defects. - Cataract formation. - Secondary eye infections or exacerbation of existing infections. - Perforation of the globe.

Ocular Lubricants (Artificial Tears): - Used for relief of dry eyes and irritation. - Typical usage is $3-4$ times per day. - Warning: Overuse (exceeding a maximum of $4$ times a day) can actually exacerbate dry eye symptoms.
Ophthalmic Vasoconstrictors: - Used for temporary relief of redness caused by minor irritants or allergic conjunctivitis. - Brands: Bausch & Lomb Allergy Drops, Clear Eyes, Comfort Eye Drops. - Contraindication: Narrow-angle glaucoma. - Dosing (Adults): $1-2$ drops up to a maximum of $4$ times daily. Not recommended for children. - Overuse Warning: Prolonged use can lead to dry eye syndrome. - Drug Interactions: - Naphazoline interacts with Tricyclic Antidepressants. - All ophthalmic vasoconstrictors interact with Monoamine Oxidase Inhibitors (MAOIs) and Beta Blockers.

Purpose: Used to detect corneal abrasions.
Definition: Topical Fluorescein Sodium is a yellow, water-soluble, dibasic acidic xanthine dye.
Procedure: 1. Instill $1$ or $2$ drops of fluorescein solution or use strips moistened with sterile water. 2. Have the patient roll their eyes to coat the surface. 3. Darken the exam room. 4. Use a Woods Lamp (UV light) to examine the eye.
Results: Corneal abrasions will glow a bright neon yellow-green. An intact cornea will not stain, though it may show slight yellow discoloration.

Combination Products: Medications containing both a corticosteroid and an antibiotic (e.g., Cortisporin, CiproDex, Cipro HC). - The hydrocortisone ( $HC$ ) component reduces inflammation in the ear canal. - Primary use: Otitis externa (external ear infection).
Contraindication: Do not use any medication with a steroid component if the tympanic membrane is perforated.
Antibiotic-only Drops: Gentamicin and Ofloxacin.
Otitis Externa Adjuncts: Acid or alcohol drops can be used to dry moisture in the ear canal.
Topical Otic Analgesics: - Agents: Auralgan and Benzocaine. - Usage: Provide pain relief for Otitis Media. - Dosing: Instill into the affected ear $3-4$ times a day or as often as every $1-2$ hours as needed for pain.

Medications: Carbamide peroxide-based products such as Debrox, Dent's Ear Wax, and Murine Ear Wax Removal.
Clinical Application: Used to soften earwax prior to irrigation.
Clinical Timing: The medication should sit in the ear for at least $15-20$ minutes before irrigation to ensure the wax is soft enough to remove.
Home Administration: - Instill $1-5$ drops (depending on canal size) twice daily for up to $4$ days. - Persistent cases: If wax is too hard to remove in-office, patients are sent home with a prescription to use for $4$ days before returning for irrigation.