Bacitracin ophthalmic - Drug Monograph

Introduction

Bacitracin ophthalmic is a topical antibiotic preparation specifically formulated for ocular use. It belongs to the polypeptide class of antibiotics and has been used in ophthalmology for decades to treat and prevent bacterial infections of the eye. This preparation is particularly valuable for its effectiveness against gram-positive organisms, which are common pathogens in ocular infections.

Mechanism of Action

Bacitracin exerts its antibacterial effect by interfering with bacterial cell wall synthesis. It specifically inhibits the dephosphorylation of the phospholipid carrier that transports peptidoglycan precursors across the cytoplasmic membrane. This disruption prevents the incorporation of these precursors into the growing peptidoglycan chain, ultimately leading to bacterial cell death. Bacitracin is primarily bactericidal against susceptible organisms and demonstrates particular efficacy against gram-positive bacteria including Staphylococcus and Streptococcus species.

Indications

Bacitracin ophthalmic ointment is FDA-approved for the treatment of superficial ocular infections caused by susceptible organisms, including:

• Bacterial conjunctivitis
• Blepharitis
• Bacterial keratitis
• Prophylaxis against infection following corneal abrasions or minor ocular procedures
• Prevention of ophthalmia neonatorum caused by susceptible organisms (though other agents are typically preferred)

Dosage and Administration

• Wash hands before application
• Tilt head backward
• Gently pull down lower eyelid to create a pouch
• Squeeze ointment into the conjunctival sac
• Avoid touching the tip of the tube to any surface to prevent contamination
• Close eye for 1-2 minutes after application
• Wipe excess ointment from eyelids with clean tissue

• Pediatric patients: Use with caution; safety and efficacy established in children
• Geriatric patients: No dosage adjustment required
• Renal/hepatic impairment: No specific recommendations due to minimal systemic absorption

Pharmacokinetics

Contraindications

• Hypersensitivity to bacitracin or any component of the formulation
• Known allergy to other polypeptide antibiotics
• Viral, fungal, or mycobacterial ocular infections (unless accompanied by appropriate antimicrobial therapy)

Warnings and Precautions

• Prolonged use may result in overgrowth of nonsusceptible organisms, including fungi
• Should not be used for deep-seated or systemic infections
• Contact dermatitis may occur with prolonged use
• Discontinue use if hypersensitivity reactions develop
• Avoid contact with soft contact lenses; may contain preservatives that can be absorbed by lenses
• Use with caution in patients with history of allergic reactions to multiple antibiotics

Drug Interactions

• No clinically significant drug interactions have been documented due to minimal systemic absorption
• Theoretical potential for reduced efficacy when used concomitantly with chloramphenicol (in vitro antagonism demonstrated)
• No interactions with systemically administered medications reported

Adverse Effects

• Transient blurred vision
• Mild ocular irritation or burning upon instillation
• Erythema of conjunctiva
• Eyelid itching or swelling

• Severe allergic reactions including anaphylaxis (extremely rare with topical use)
• Superinfections with resistant organisms
• Severe contact dermatitis
• Corneal ulceration (with improper use)

Monitoring Parameters

• Clinical signs of infection resolution (reduced redness, discharge, discomfort)
• Signs of hypersensitivity reactions (increased redness, swelling, itching)
• Development of superinfection (worsening symptoms after initial improvement)
• Visual acuity changes
• Corneal integrity in patients with keratitis
• Patient compliance with treatment regimen

Patient Education

• Complete the full course of treatment even if symptoms improve
• Do not share medication with others
• Wash hands before and after application
• Avoid wearing contact lenses during treatment unless directed by ophthalmologist
• Wait at least 10 minutes after instillation before inserting contact lenses
• Do not touch the tip of the tube to any surface to prevent contamination
• Store at room temperature away from moisture and heat
• Discard tube 4 weeks after opening
• Report any worsening symptoms, severe irritation, or rash around eyes to healthcare provider
• Temporary blurred vision may occur after application; avoid driving or operating machinery until vision clears

References

1. American Academy of Ophthalmology. (2021). Basic and Clinical Science Course: External Disease and Cornea. 2. Bartlett, J. D., & Jaanus, S. D. (2021). Clinical Ocular Pharmacology. Elsevier. 3. Gilbert, D. N., et al. (2020). The Sanford Guide to Antimicrobial Therapy. 4. FDA prescribing information for bacitracin ophthalmic ointment. 5. Yanoff, M., & Duker, J. S. (2019). Ophthalmology. Elsevier. 6. ASCRS and ASRS Joint Task Force on Ophthalmic Antibiotics. (2018). Guidelines for the Use of Topical Ophthalmic Antibiotics.