NEOSPORIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEOSPORIN (NEOSPORIN).
Neosporin is a combination of three antibiotics: neomycin (aminoglycoside) inhibits bacterial protein synthesis by binding to 30S ribosomal subunit; polymyxin B (polymyxin) disrupts bacterial cell membrane integrity; bacitracin (polypeptide) inhibits bacterial cell wall synthesis by interfering with dephosphorylation of the lipid carrier.
| Metabolism | Neomycin is minimally absorbed; absorbed fraction undergoes hepatic metabolism and renal excretion. Polymyxin B and bacitracin are not significantly absorbed through intact skin; systemic absorption minimal. |
| Excretion | Renal excretion accounts for >90% of elimination; primarily glomerular filtration with minimal tubular secretion. Small biliary/fecal elimination (<5%). |
| Half-life | Variable based on severity of renal impairment. Normal renal function: 2-3 hours for neomycin (main component); polymyxin B: 4-6 hours. In anuria: half-life extends to 72-96 hours for neomycin. |
| Protein binding | Neomycin: negligible (<10%), primarily to albumin; polymyxin B: approximately 60% bound to plasma proteins. |
| Volume of Distribution | Neomycin: 0.4 L/kg (confined to extracellular fluid); polymyxin B: 0.6 L/kg (largely extracellular). Vd increases with edema or burns. |
| Bioavailability | Oral: <3% (neomycin), <1% (polymyxin B); topical (intact skin): <1%; ophthalmic/otic: minimal systemic absorption. |
| Onset of Action | Topical application to intact skin: no systemic absorption; onset of antimicrobial effect within 12-24 hours. Ophthalmic/otic: 24-48 hours. |
| Duration of Action | Topical: 8-12 hours for antibacterial effect; requires TID-QID dosing to maintain therapeutic levels. Systemic effects negligible due to poor absorption. |
| Brand Substitutes | Nebazine Ointment, Neosporin Skin Ointment, Nebaspor Ointment, Jisporin Ointment, Nexporin Ointment |
Apply a thin layer topically to the affected area 1-3 times daily. May be covered with a sterile bandage.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dose adjustment required for topical use. Systemic absorption is minimal. |
| Liver impairment | No dose adjustment required for topical use. Systemic absorption is minimal. |
| Pediatric use | Apply a thin layer topically to the affected area 1-3 times daily. Safety and efficacy in children under 2 years have not been established. |
| Geriatric use | No specific dose adjustment required. Use caution in elderly with impaired skin integrity or reduced renal function due to potential for increased systemic absorption. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NEOSPORIN (NEOSPORIN).
| Breastfeeding | Topical application results in negligible systemic absorption; therefore, transfer into breast milk is minimal. The M/P ratio is not established, but the risk to the nursing infant is considered low. Avoid application to the breast area to prevent infant ingestion. |
| Teratogenic Risk | Teratogenic risk is low based on animal studies and limited human data. In the first trimester, no increased risk of major congenital malformations has been reported for topical neomycin/polymyxin B/bacitracin. In the second and third trimesters, caution is advised due to potential ototoxicity and nephrotoxicity from systemic absorption of neomycin, though topical application minimizes risk. Avoid prolonged treatment over large areas or on broken skin. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to any component (neomycin, polymyxin B, bacitracin); history of allergic reaction to aminoglycosides; use in eyes or for internal use.
| Precautions | Potential for allergic contact dermatitis (especially neomycin); prolonged use may lead to overgrowth of non-susceptible organisms; avoid use in large areas of broken skin, deep puncture wounds, or serious burns due to risk of systemic absorption; ototoxicity and nephrotoxicity with prolonged use on damaged skin (rare). |
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| Fetal Monitoring | No specific maternal or fetal monitoring is required for topical use; however, monitor for signs of allergic reactions or skin irritation. Use caution with extensive application or open wounds. |
| Fertility Effects | No known effects on fertility. Topical administration results in minimal systemic exposure and is not associated with reproductive toxicity in animal studies. |