Polymyxin B/trimethoprim

Treats bacterial conjunctivitis and blepharoconjunctivitis due to susceptible staphylococci, streptococci, H. influenzae and P. aeruginosa specified by the label. Pseudomonas efficacy evidence involved fewer than ten infections; in-vitro activity does not establish a universal corneal-ulcer or resistant-organism regimen.

The selected U.S. product is prescription ophthalmic solution with ANDA marketing status. It is not indicated for preventing or treating ophthalmia neonatorum; safety/effectiveness below two months is not established. Diagnosis matters: the label does not establish treatment for viral/allergic conjunctivitis or systemic infections.

One drop in each affected eye every three hours, maximum six doses per day, for 7–10 days. The label provides this schedule without a separate pediatric weight-based dose. Below two months, treatment is not established. Confirm affected eyes, dose timing and duration with the prescriber rather than substitute oral trimethoprim or systemic polymyxin dosing.

Avoid touching the tip to the eye, fingers or another surface; do not inject into the eye or use a systemic route. Do not wear contacts during symptomatic bacterial infection. The selected label has no renal, hepatic or dialysis adjustment table; low measured systemic absorption does not prove zero exposure or support a systemic dose conversion.

Known hypersensitivity to any ingredient contraindicates the selected solution. Review prior reactions to trimethoprim, polymyxin B and formulation ingredients. Trimethoprim sulfate is a salt; this product is not the trimethoprim/sulfamethoxazole combination. Do not infer the same allergy or dose rules from a different antibiotic product.

No boxed warning appears in the selected current ophthalmic label. This does not negate its serious hypersensitivity reports, topical-route restriction or neonatal indication exclusion.

Burning, stinging, itching and increased redness are reported, sometimes on instillation or later in treatment. Allergy can include eyelid swelling, tearing and rash around the eye. Anaphylaxis and SJS/TEN are reported without reliable rates. The label mentions photosensitivity with oral trimethoprim; that is not a quantified ophthalmic-event frequency.

The full selected ophthalmic label specifies no established drug–drug interaction or routine laboratory-monitoring schedule. Review other ocular products and systemic therapy with the clinician/pharmacist. Systemic trimethoprim/sulfamethoxazole and injectable polymyxin safety algorithms cannot be assumed to describe these eye drops. No unsourced universal separation interval is supplied.

Avoid contact lenses while symptomatic infection is present and avoid tip contamination. The solution contains benzalkonium chloride 0.004%; follow clinician advice for other eye medicines and lens resumption rather than use an unrelated glaucoma-product lens instruction.

Safety/effectiveness below two months is not established. The selected geriatric section reports no overall safety/effectiveness differences compared with other adults; it does not remove individual eye-disease or allergy concerns.

No numerical organ-function adjustment or dialysis supplemental regimen is established in this ophthalmic label. Systemic exposure was small but detectable in a limited volunteer study. Assess the individual patient rather than claim proven absence of renal/hepatic risk.

The label describes trimethoprim’s folate-related concern and oral animal/human data; use in pregnancy only when expected benefit justifies fetal risk. Ophthalmic pregnancy data and polymyxin reproductive data are limited. Human milk excretion of this product is unknown and the label advises caution during nursing; do not claim zero infant exposure or equate oral combination studies with ophthalmic outcomes.

Trimethoprim inhibits bacterial dihydrofolate reductase, impairing folate-dependent nucleic-acid/protein synthesis. Polymyxin B disrupts susceptible gram-negative bacterial membranes. The broad in-vitro organism lists are separate from the narrower clinically labeled infection/organism claims.

In eleven volunteers receiving two drops, measured peak serum trimethoprim was about 0.03 mcg/mL and polymyxin B about 1 unit/mL. These observations do not provide a validated systemic half-life, accumulation model, therapeutic blood target or renal dose algorithm for the ophthalmic course.

Assess ocular symptoms, treatment response, hypersensitivity and possible superinfection. The selected label specifies no routine CBC, renal panel or serum drug levels for this topical course. Failure to improve or worsening pain/swelling warrants clinical reassessment rather than extending antibiotic use indefinitely.

Use the prescribed affected-eye schedule, keep the tip clean and avoid contact lenses during infection. Stop and contact the clinician for persistent/increasing redness, irritation, swelling or pain; seek urgent care for serious allergy. Keep the bottle protected from light and do not inject or repurpose the drops.

Selected sterile Bausch & Lomb ophthalmic solution is a 10 mL controlled-drop plastic bottle, NDC 24208-315-10, prescription only. Confirm the package and ingredients rather than rely on an antibiotic brand-name assumption.

Each mL supplies polymyxin B 10,000 units and trimethoprim 1 mg through their sulfate salts. Benzalkonium chloride preservative is 0.004%. This is topical eye solution, not an injectable or oral combination.

Store at 15–25°C and protect from light. Retain in its carton until use because the selected bottle does not meet the USP light-resistance packaging specification. Keep the applicator uncontaminated. The reviewed label supplies no universal after-opening discard period; follow the actual dispensing instructions.