NEOMYCIN & POLYMYXIN B SULFATES & BACITRACIN ZINC & HYDROCORTISONE
Clinical safety rating: safe
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
Neomycin, polymyxin B, and bacitracin are antibiotics that inhibit bacterial protein synthesis, disrupt cell membrane integrity, and interfere with cell wall synthesis, respectively. Hydrocortisone is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis.
| Metabolism | Neomycin is minimally metabolized; polymyxin B is not significantly metabolized; bacitracin is not metabolized; hydrocortisone is hepatically metabolized primarily by CYP3A4. |
| Excretion | Neomycin: >90% renal (unchanged) after parenteral; polymyxin B: ~60% renal (unchanged) over 72h; bacitracin: >90% renal (unchanged) after IM; hydrocortisone: hepatic metabolism, metabolites renally eliminated (<1% unchanged). Topical: negligible systemic absorption across intact skin (except bacitracin may be minimally absorbed). |
| Half-life | Neomycin: 2-3h (normal renal); polymyxin B: 4-6h (normal renal), prolonged to 2-3 days in renal impairment; bacitracin: ~1.5h after IM; hydrocortisone: 1.5-2h (plasma). Topical: systemic levels negligible. |
| Protein binding | Neomycin: <30% bound; polymyxin B: ~50-60% bound; bacitracin: ~70-80% bound; hydrocortisone: ~90% bound to corticosteroid-binding globulin (CBG) and albumin. |
| Volume of Distribution | Neomycin: 0.2-0.4 L/kg (limited to extracellular fluid); polymyxin B: 0.6-1.0 L/kg; bacitracin: ~0.3 L/kg (IM); hydrocortisone: ~0.4 L/kg. Topical: negligible systemic Vd. |
| Bioavailability | Topical ophthalmic/otic: negligible systemic bioavailability (<0.1% for neomycin, polymyxin B, bacitracin; hydrocortisone minimally absorbed); IM bacitracin: ~100% (not given IV); oral (neomycin): <3% (used for gut decontamination). |
| Onset of Action | Topical (ophthalmic/otic): anti-infective effect within 24h; hydrocortisone anti-inflammatory effect within hours; otic suspension: symptomatic relief within 24h. IM (bacitracin): within 1h. |
| Duration of Action | Topical: continued anti-infective effect over course of treatment (typically 7-10 days); anti-inflammatory effect of hydrocortisone persists ~6-12h post-dose. IM bacitracin: 4-6h. Otic: symptom relief for hours after each dose. |
Apply to affected area 3-4 times daily. Not for use in eyes.
| Dosage form | OINTMENT |
| Renal impairment | No adjustment necessary for ophthalmic/otic/topical use due to minimal systemic absorption. |
| Liver impairment | No adjustment necessary for ophthalmic/otic/topical use due to minimal systemic absorption. |
| Pediatric use | Apply to affected area 3-4 times daily. Safe for children >2 years; use with caution in infants due to potential for systemic absorption. |
| Geriatric use | No specific adjustment required. Use caution with prolonged use due to potential for increased systemic absorption with thinner skin. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
| FDA category | Animal |
| Breastfeeding | Minimal systemic absorption of topical components; unlikely to appear in breast milk. M/P ratio not available. Corticosteroids are excreted in milk but at low doses. Caution with prolonged use on large areas. Generally considered compatible with breastfeeding. |
| Teratogenic Risk | Pregnancy Category C. Neomycin and polymyxin B sulfate are poorly absorbed systemically, but bacitracin zinc is nephrotoxic if absorbed. Hydrocortisone is a corticosteroid; systemic absorption may increase risk of orofacial clefts (first trimester) and adrenal suppression (third trimester). Limited human data; risk cannot be excluded. Use only if potential benefit justifies risk. |
■ FDA Black Box Warning
None
| Common Effects | topical infections |
| Serious Effects |
["Hypersensitivity to any component; fungal or viral skin infections (e.g., herpes simplex, varicella); tuberculosis skin lesions; ophthalmic use."]
| Precautions | ["Prolonged use may lead to superinfection or systemic absorption of corticosteroids; avoid use on large areas of broken skin or near eyes; not for ophthalmic use; may cause ototoxicity if absorbed systemically."] |
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| Fetal Monitoring | Monitor for signs of systemic toxicity (ototoxicity, nephrotoxicity) if applied to damaged skin. No specific fetal monitoring required unless signs of adrenal suppression in mother. Assess fetal growth if high-dose corticosteroids used systemically. |
| Fertility Effects | No known effects on fertility with topical use. No human studies. Animal studies not found. |