Polytrim®
Polymyxin B / Trimethoprim · ophthalmic solution
Antibiotic
Approved uses
Acute bacterial conjunctivitis
1 drop in the affected eye(s) every 3 hours, maximum 6 doses per day, for 7 to 10 days in mild to moderate infection
Clinical cure in 96% of children by day 7 to 10, matching moxifloxacin.
Bacterial blepharoconjunctivitis
1 drop in the affected eye(s) every 3 hours, maximum 6 doses per day, for 7 to 10 days in mild to moderate infection
Contraindications
Known hypersensitivity to any component of the product.
Available FormsOphthalmic solution, 10 mL opaque white LDPE dispenser bottle, polymyxin B sulfate 10,000 units/mL, trimethoprim sulfate equivalent to 1 mg/mL, benzalkonium chloride 0.04 mg/mL preservative
Mechanism of ActionTrimethoprim binds and reversibly inhibits bacterial dihydrofolate reductase, blocking production of tetrahydrofolic acid from dihydrofolic acid, and because that binding is stronger for the bacterial than the mammalian enzyme it selectively interferes with bacterial nucleic acid and protein synthesis across gram-positive and gram-negative ophthalmic pathogens. Polymyxin B, a cyclic lipopeptide, is bactericidal for a variety of gram-negative organisms, especially Pseudomonas aeruginosa, and increases bacterial cell membrane permeability by interacting with the membrane phospholipids.
Warnings & Precautions
- Route restriction: Not for injection into the eye.
- Hypersensitivity reaction: Discontinue use if one occurs.
- Ophthalmia neonatorum: Not indicated for prophylaxis or treatment.
- Superinfection: Prolonged use may allow overgrowth of nonsusceptible organisms, including fungi.
- Contact lens wear: Lenses should not be worn while signs and symptoms of ocular bacterial infection are present.
Common Side Effects
- Ocular, most frequent: Local irritation with increased redness, burning, stinging, and/or itching, on instillation, within 48 hours, or at any time with extended use.
- Ocular hypersensitivity: Multiple reports of lid edema, itching, increased redness, tearing, and/or circumocular rash.
- Systemic, serious: Stevens-Johnson syndrome and toxic epidermal necrolysis, and anaphylaxis, have been reported.
- Photosensitivity: Reported in patients taking oral trimethoprim.
Pregnancy & LactationPregnancy: Trimethoprim was teratogenic in rats at oral doses 40 times the human dose and, in some rabbit studies, increased fetal loss at oral doses 6 times the human therapeutic dose; no animal reproduction studies exist for polymyxin B, and because folic acid metabolism may be affected, use only if the potential benefit justifies the potential fetal risk.
Lactation: Excretion in human milk is unknown, so caution is warranted in a nursing woman.
Pediatric UseSafety and effectiveness below 2 months of age have not been established.