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Trimethoprim Sulfate / Polymyxin B Sulfate

Pronunciation: try-METH-oh-prim SULL-fate/pahl-ee-MIX-in BEE SULL-fate
Class: Antibiotic combination

Trade Names

- Ophthalmic Solution 1 mg/mL trimethoprim sulfate and 10,000 units/g polymyxin B sulfate



Blocks production of tetrahydrofolic acid by inhibiting the enzyme dihydrofolate reductase.

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Polymyxin B

Interacts with phospholipid components of bacterial cell membranes, increasing cell wall permeability.

Indications and Usage

Treatment of surface ocular bacterial infections, including acute bacterial conjunctivitis and blepharoconjunctivitis caused by susceptible organisms.


Standard considerations.

Dosage and Administration

Adults and children 2 mo of age and older

Topical Instill 1 drop in the affected eye(s) every 3 h (max, 6 doses/day) for 7 to 10 days.


Store at controlled room temperature (59° to 77°F). Keep bottle tightly capped and protect from light.

Drug Interactions

None well documented.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Local irritation (including increased redness, burning, stinging, and itching); hypersensitivity (including lid edema, itching, increased redness, tearing, and circumocular rash).


Photosensitivity (has occurred with oral trimethoprim).



Category C .




Safety and efficacy not established in children younger than 2 mo of age.


Prolonged use may result in bacterial or fungal overgrowth of nonsusceptible microorganisms.

Patient Information

  • Review prescribed dosing schedule with patient, family, or caregiver.
  • Remind patient, family, or caregiver that solution is for use in the eye only.
  • Teach patient, family, or caregiver proper technique for instilling solution: wash hands; do not allow tip of dropper bottle to touch eye, eyelid, fingers, or any other surface. Tilt head back, look up; pull lower eyelid down to form pocket; place prescribed number of drops in the pocket. Look downward before closing eye. Do not rub eye.
  • Advise patient, family, or caregiver that if more than 1 topical ophthalmic drug is being used, instill eye drops first, wait at least 5 min, and instill ointment last.
  • Inform patient that temporary blurred vision and stinging of the eye are the most common adverse reactions and to contact health care provider if they occur and are bothersome.
  • Advise patient to contact eye doctor if eye or eyelid inflammation is noted or if eye symptoms do not improve or worsen.
  • Advise patient that the entire course of therapy must be completed to ensure max benefit and to complete full course of therapy even if symptoms have resolved.
  • Instruct patient not to wear contact lenses during treatment.
  • Remind patient, family, or caregiver that follow-up eye examinations may be necessary while using this medication and to keep appointments.

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