Polymyxin B Drops Dosage for Bacterial Conjunctivitis
For bacterial conjunctivitis, polymyxin B ophthalmic drops should be instilled as one drop in the affected eye(s) every three hours (maximum of 6 doses per day) for 7 to 10 days. 1
Dosing Regimen Details
The FDA-approved dosage for polymyxin B ophthalmic solution is clear and straightforward:
- Frequency: Every three hours
- Maximum doses: 6 doses per day
- Duration: 7 to 10 days
- Application: One drop per affected eye
Treatment Considerations
Efficacy Comparison
While polymyxin B is effective for bacterial conjunctivitis, it's worth noting that newer fluoroquinolones may offer faster resolution of symptoms:
- A comparative study showed that moxifloxacin 0.5% administered three times daily resolved symptoms more quickly than polymyxin B/trimethoprim combination (81% vs 44% resolution at 48 hours) 2
- However, polymyxin B remains a viable treatment option, particularly for mild to moderate infections
Clinical Response Indicators
Positive response to antibiotic therapy should be monitored through:
- Reduced discharge
- Decreased eyelid edema and conjunctival injection
- Reduced pain
- Initial re-epithelialization 3
Treatment Modifications
If the patient doesn't show improvement within 48 hours, consider:
- Changing the antibiotic type
- Adjusting concentration or frequency
- Obtaining cultures if not previously done 3
Patient Education and Supportive Care
In addition to antibiotic therapy, patients should be advised to:
- Use warm compresses to soften discharge and loosen crusts 4
- Practice strict hygiene measures to prevent spread 4
- Avoid sharing towels, pillowcases, and personal items 4
- Discontinue contact lens wear until infection resolves 4
Special Considerations
Contact Lens Wearers
- Discontinue lens wear until infection completely resolves
- Consider switching to new lenses after resolution to prevent re-infection 4
When to Refer
Refer to an ophthalmologist if the patient experiences:
- No response to therapy after 3-4 days
- Moderate to severe pain
- Decreased vision
- Corneal involvement 4
Common Pitfalls to Avoid
- Inadequate duration: Don't stop treatment prematurely when symptoms improve; complete the full 7-10 day course
- Overuse: Don't exceed 6 doses per day as this may increase risk of toxicity
- Prolonged use: Avoid extended use beyond recommendation as this can lead to antibiotic resistance
- Inadequate follow-up: Failure to reassess after 48 hours may miss treatment failures
- Missing concurrent conditions: Ensure underlying conditions (dry eye, entropion, etc.) are also addressed 4
Remember that while polymyxin B is effective for bacterial conjunctivitis, newer fluoroquinolones may offer advantages in terms of dosing convenience and speed of symptom resolution for some patients.