Polytrim Dosing for Children
For children 2 months and older, the standard dose of Polytrim (polymyxin B/trimethoprim) ophthalmic solution is 1 drop in the affected eye(s) 4 times daily for 7 days. 1
Age Restrictions
- Safety and effectiveness have NOT been established in children below 2 months of age 1
- For children ≥2 months: use the standard adult dosing regimen without adjustment
Dosing Regimen Details
The FDA-approved dosing is straightforward:
- Frequency: 1 drop four times daily
- Duration: 7 days of treatment
- Route: Topical ophthalmic administration
- No weight-based adjustment needed - same dose regardless of child's size 1
Clinical Context
Polytrim is commonly used for bacterial conjunctivitis in children, where it demonstrates good efficacy. Clinical studies show that approximately 95% of pediatric patients with bacterial conjunctivitis achieve cure or improvement within 7 days using this regimen 2. The medication is generally well-tolerated, with patients reporting being very comfortable or moderately comfortable in 89% of cases 2.
Important Caveats
- Do not use in infants under 2 months - this is a critical safety restriction 1
- The four-times-daily dosing may be less convenient than newer fluoroquinolones (which require only 3 times daily), but Polytrim remains clinically effective and significantly more cost-effective 3
- While one comparative study suggested slower symptom resolution compared to moxifloxacin at 48 hours 4, a larger randomized trial demonstrated equivalent clinical cure rates by day 7-10 (96% vs 95%) 3
Practical Administration
Instill 1 drop into the conjunctival sac of the affected eye(s) at approximately 6-hour intervals throughout the day (e.g., morning, midday, late afternoon, bedtime) to maintain consistent antimicrobial coverage.