What is the recommended dose of gentamicin (ophthalmic solution) for treating bacterial conjunctivitis?

Gentamicin Ophthalmic Solution Dosage for Bacterial Conjunctivitis

For bacterial conjunctivitis, instill one or two drops of gentamicin ophthalmic solution into the affected eye(s) every four hours. In severe infections, dosage may be increased to as much as two drops every hour. 1

Dosing Recommendations Based on Severity

Mild to Moderate Bacterial Conjunctivitis

• One to two drops in affected eye(s) every four hours
• Continue for 5-7 days
• Patients should be advised to return for follow-up if no improvement is seen within 3-4 days

Severe Bacterial Conjunctivitis

• One to two drops in affected eye(s) every hour initially
• As symptoms improve, frequency can be reduced to every four hours
• Continue treatment until 24-48 hours after resolution of symptoms

Efficacy and Considerations

Gentamicin is an aminoglycoside antibiotic that has demonstrated effectiveness in treating bacterial conjunctivitis. Clinical studies show that gentamicin successfully cures or improves symptoms in approximately 88% of patients with bacterial conjunctivitis 2.

However, there are important considerations when using gentamicin:

• An epidemiologic study found that infants in neonatal intensive care settings due to low birth weight and/or low gestational age have an increased incidence of gram-negative conjunctivitis that is often resistant to gentamicin 3
• For severe infections, particularly those caused by Methicillin-resistant Staphylococcus aureus (MRSA), laboratory testing may be needed to guide therapy, as MRSA organisms are resistant to many commercially available topical antibiotics 3

Special Populations and Situations

Gonococcal Conjunctivitis

• Gentamicin alone is not sufficient - systemic antibiotic therapy is necessary
• If corneal involvement is present, topical treatment as for bacterial keratitis should be added
• Patients should be seen daily until resolution of the conjunctivitis 3

Neonatal Conjunctivitis

• Caution is advised as resistance to gentamicin has been reported in neonatal intensive care settings
• Consider alternative antibiotics based on local resistance patterns 3

Preparation of Fortified Gentamicin (14 mg/ml) if Needed for Severe Infections

For severe infections requiring higher concentrations:

1. Withdraw 2 ml from an injectable vial of intravenous gentamicin (40 mg/ml)
2. Add the withdrawn 2 ml to a 5-ml bottle of gentamicin ophthalmic solution to give a 14 mg/ml solution
3. Refrigerate and shake well before instillation 3

When to Refer to an Ophthalmologist

Patients with conjunctivitis should be referred to an ophthalmologist if they experience:

• Visual loss
• Moderate or severe pain
• Severe, purulent discharge
• Corneal involvement
• Conjunctival scarring
• Lack of response to therapy within 3-4 days
• Recurrent episodes
• History of HSV eye disease
• History of immunocompromise 3

By following these dosing guidelines and monitoring recommendations, gentamicin ophthalmic solution can effectively treat most cases of bacterial conjunctivitis while minimizing the risk of complications.