From the FDA Drug Label
DOSAGE AND ADMINISTRATION Adults: In mild to moderate infections, instill one drop in the affected eye(s) every three hours (maximum of 6 doses per day) for a period of 7 to 10 days. Pediatric Use: Clinical studies have shown Trimethoprim and Polymyxin B Sulfate Ophthalmic Solution to be safe and effective for use in pediatric patients over two months of age. The dosage regimen is the same as for adults. The Polytrim dosing regimen is:
- One drop in the affected eye(s) every three hours
- Maximum of 6 doses per day
- For a period of 7 to 10 days 1
From the Research
Polytrim (polymyxin B-trimethoprim) eye drops are typically dosed as 1 drop in the affected eye(s) every 3 hours (4 times daily) for 7-10 days for bacterial conjunctivitis. For more severe infections, dosing may be increased to every 3 hours while awake for the first 24-48 hours, then reduced to 4 times daily until the infection resolves. This dosing regimen is supported by a study published in 2013 2, which compared the efficacy of polymyxin B-trimethoprim with moxifloxacin in the treatment of acute conjunctivitis in children, and found that polymyxin B-trimethoprim was an effective treatment with a clinical response rate that did not differ from moxifloxacin.
Key Considerations
- Before application, wash hands thoroughly and avoid touching the dropper tip to any surface to prevent contamination.
- Tilt the head back, pull down the lower eyelid to form a pocket, look up, and place the drop into the pocket.
- Close the eyes gently for 1-2 minutes to allow absorption and prevent drainage through the tear duct.
- Wait at least 5 minutes before using any other eye medications.
Mechanism of Action
Polytrim combines polymyxin B, which disrupts bacterial cell membranes, with trimethoprim, which inhibits bacterial DNA synthesis, providing broad-spectrum coverage against many common eye pathogens.
Treatment Duration
Complete the full course of treatment even if symptoms improve to ensure complete eradication of the infection and prevent antibiotic resistance, as supported by studies such as the one published in 1988 3, which found that trimethoprim-polymyxin B sulphate ophthalmic ointment was effective in the treatment of bacterial conjunctivitis.
Additional Considerations
- The development of resistance of typical germs to all antibiotic groups is alarming and should influence therapeutic behavior, as noted in a study published in 2012 4.
- Fluoroquinolones, such as moxifloxacin, show good activity in the treatment of acute bacterial conjunctivitis but should be saved for severe infections due to their broad spectrum of activity.