NEO-POLYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEO-POLYCIN (NEO-POLYCIN).
Neomycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, inhibiting protein synthesis. Polymyxin B is a polypeptide antibiotic that disrupts bacterial cell membrane permeability by interacting with phospholipids. Bacitracin inhibits bacterial cell wall synthesis by interfering with dephosphorylation of the lipid carrier.
| Metabolism | Systemic absorption is minimal after ophthalmic administration. If absorbed, neomycin is excreted largely unchanged by glomerular filtration; polymyxin B and bacitracin are primarily excreted unchanged in urine. |
| Excretion | Neomycin: ~30-50% of absorbed dose excreted renally as unchanged drug; unabsorbed drug eliminated fecally. Polymyxin B: minimal renal excretion (<1% of dose); primarily eliminated via non-renal routes, possibly biliary or metabolic. Bacitracin: negligible renal excretion after topical use; systemic absorption minimal. |
| Half-life | Neomycin: 2-3 hours in patients with normal renal function; prolonged to 12-24 hours in renal impairment. Polymyxin B: 6-8 hours. Bacitracin: 1.5 hours (if absorbed); typically not systemically available. |
| Protein binding | Neomycin: low (~15-30%) to serum proteins. Polymyxin B: moderate (~50-60%) to plasma proteins. Bacitracin: high (~80%) to plasma proteins, but binding is reversible. |
| Volume of Distribution | Neomycin: ~0.5 L/kg (confined to extracellular fluid); minimal tissue penetration. Polymyxin B: ~0.3-0.5 L/kg. Bacitracin: negligible systemic distribution due to toxicity limiting systemic use. |
| Bioavailability | Topical (ophthalmic/skin): essentially zero systemic bioavailability (<0.1% absorbed); acts locally. Oral: neomycin ~3% absorbed; polymyxin B and bacitracin not absorbed orally. Intramuscular: neomycin ~100% absorbed (but not used systemically due to toxicity). |
| Onset of Action | Topical (ophthalmic): onset within 30 minutes for bacterial inhibition; clinical improvement noted within 24-48 hours. Topical (skin): similar onset, 30 minutes to hours. |
| Duration of Action | Topical (ophthalmic): duration 4-6 hours, requiring frequent application (every 3-4 hours). Topical (skin): 6-8 hours; reapplication needed. |
| Molecular Weight | 328.48 |
Apply a thin layer to the affected area 3 to 4 times daily. Use a unit-dose ointment or eye drops: 1 to 2 drops in the affected eye(s) every 4 to 6 hours, or more frequently as needed.
| Dosage form | OINTMENT |
| Renal impairment | No dosage adjustment required for topical ophthalmic or dermatologic use; systemic absorption negligible. For topical application on extensive burn areas or wounds, monitor renal function and consider dose reduction if GFR < 30 mL/min due to potential polymyxin B accumulation. |
| Liver impairment | No dosage adjustment required; hepatic impairment does not significantly alter systemic exposure with topical use. For extensive use, no specific Child-Pugh based recommendations. |
| Pediatric use | Infants and children: Apply thin layer to affected area 3 to 4 times daily. Ophthalmic: 1 drop in affected eye(s) every 4 to 6 hours. Weight adjustments not required due to minimal systemic absorption. |
| Geriatric use | No specific dose adjustment; use same as adult dosing. Caution in elderly with renal impairment if applied on large body surface areas; monitor for systemic effects. |
| 1st trimester | Avoid unless clearly needed. Topical use may be safe if minimal systemic absorption. Consider risk of aminoglycoside ototoxicity and nephrotoxicity. |
| 2nd trimester | Use with caution. Systemic absorption is low, but theoretical risk of fetal harm exists. |
| 3rd trimester | Use with caution. Near term, theoretical risk of fetal ototoxicity and nephrotoxicity. |
Clinical note
Comprehensive clinical and safety monograph for NEO-POLYCIN (NEO-POLYCIN).
| Placental transfer | Minimal to negligible via topical route; systemic absorption is <0.5%. If systemic levels occur, aminoglycosides cross the placenta. |
| Breastfeeding | Topical application to small areas is likely compatible with breastfeeding. Avoid application to breast or nipple area. Systemic absorption is minimal; however, aminoglycosides may be excreted in breast milk in low amounts, potentially altering infant gut flora. |
■ FDA Black Box Warning
Neomycin is nephrotoxic and ototoxic, especially in patients with renal impairment or prolonged use. Systemic absorption from ophthalmic use is minimal, but caution is advised.
| Serious Effects |
Hypersensitivity to any componentPerforated eardrum (otic use)Severe renal impairment (systemic use)
| Precautions | Risk of hypersensitivity reactions, including cross-sensitivity with other aminoglycosides., Prolonged use may result in overgrowth of nonsusceptible organisms, including fungi., Do not use for irrigation or in closed body cavities due to risk of systemic absorption and toxicity. |
| Food/Dietary | None known. No dietary restrictions associated with topical use. |
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| Lactation Rating | L2 - Probably Compatible |
| Teratogenic Risk | Neomycin, polymyxin B, and bacitracin are not absorbed systemically from ophthalmic or topical use to a significant degree. Therefore, the risk of teratogenicity is considered low. No specific fetal risks have been identified in animal studies. FDA Pregnancy Category C: Animal reproduction studies have not been conducted; systemic exposure is negligible. First trimester: no known risk; second and third trimesters: no known risk. |
| Fetal Monitoring | No specific monitoring required due to negligible systemic absorption. Routine prenatal care recommended. Monitor for local hypersensitivity or allergic reactions. |
| Fertility Effects | No known effects on fertility; systemic absorption is minimal, and no reproductive toxicity has been reported. |
| Clinical Pearls |
| Neomycin and polymyxin B sulfates combination is a topical antibiotic for superficial bacterial infections. Avoid use in large body surface areas or for extended periods to minimize risk of systemic absorption and nephrotoxicity/ototoxicity from neomycin. Contraindicated in patients with known hypersensitivity to any component. Not effective against fungal or viral infections. For external use only; avoid contact with eyes. |
| Patient Advice | Apply a thin layer to the affected area as prescribed. · Do not use on large areas of skin or for longer than directed without consulting your doctor. · Avoid contact with eyes, nose, mouth, or broken skin. · Notify your doctor if the condition persists or worsens after a few days. · Do not use this medication if you are allergic to neomycin, polymyxin B, or any of its ingredients. · Inform your physician if you are pregnant, planning to become pregnant, or breastfeeding. |