NEOMYCIN SULFATE-POLYMYXIN B SULFATE-HYDROCORTISONE
Clinical safety rating: safe
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
Neomycin sulfate is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis in susceptible bacteria. Polymyxin B sulfate is a polypeptide antibiotic that disrupts bacterial cell membrane integrity by interacting with phospholipids. Hydrocortisone is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis, and modulating immune cell activity.
| Metabolism | Neomycin: primarily excreted unchanged in urine; minimally metabolized. Polymyxin B: not significantly metabolized; excreted unchanged in urine. Hydrocortisone: metabolized primarily in the liver via reduction and conjugation; also undergoes extrahepatic metabolism. |
| Excretion | Neomycin is excreted primarily unchanged in feces (97%) after oral administration; absorbed fraction is renally excreted (30-50%). Polymyxin B is renally excreted (60%) with some biliary excretion. Hydrocortisone is metabolized hepatically and excreted renally as conjugates. |
| Half-life | Neomycin: 2-3 hours (renal impairment: up to 12-24 hours). Polymyxin B: 4.5-6 hours (prolonged in renal failure). Hydrocortisone: 1.5-2 hours. |
| Protein binding | Neomycin: minimal binding (0-30%). Polymyxin B: approximately 80% bound to plasma proteins. Hydrocortisone: 90-93% bound to corticosteroid-binding globulin and albumin. |
| Volume of Distribution | Neomycin: 0.2-0.4 L/kg (largely extracellular). Polymyxin B: 0.6-0.9 L/kg (distributes to tissues). Hydrocortisone: 0.4 L/kg (total body water). |
| Bioavailability | Oral neomycin: <3% absorbed. Oral polymyxin B: negligibly absorbed (<1%). Hydrocortisone: oral ~96%; topical/otic: minimal systemic absorption. |
| Onset of Action | Topical ophthalmic: within 24-48 hours for anti-inflammatory effect; otic: within 1-2 days for symptom relief. |
| Duration of Action | Therapeutic effect persists for the duration of treatment; inflammation reduction lasts while applied. No prolonged duration after cessation. |
| Molecular Weight | Neomycin sulfate: 908.88 g/mol; Polymyxin B sulfate: 1301.56 g/mol; Hydrocortisone: 362.46 g/mol. Mixture, no single value. |
Otic: Instill 3-5 drops into the affected ear(s) 3-4 times daily; for acute otitis externa, a wick may be used initially.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | Neomycin: In patients with renal impairment (CrCl <50 mL/min), reduce dose or avoid use due to potential ototoxicity and nephrotoxicity; for otic use, systemic absorption is minimal but caution is advised; no specific GFR-based adjustments are established for otic formulation. |
| Liver impairment | No specific dose adjustment recommended based on Child-Pugh score; however, caution is advised in severe hepatic impairment due to potential for increased systemic absorption of corticosteroids. |
| Pediatric use | Children: Instill 2-3 drops into the affected ear(s) 3-4 times daily; safety and efficacy not established for children <2 years. |
| Geriatric use | Elderly patients may have increased risk of ototoxicity and nephrotoxicity from neomycin component; monitor renal function and audiometry if prolonged use; no specific dose adjustment recommended for otic use. |
| 1st trimester | Avoid unless clearly needed. Otic and topical use considered safe as systemic absorption is minimal. However, if used on broken skin or for prolonged periods, consider potential ototoxicity and nephrotoxicity, though risk low. |
| 2nd trimester | Avoid unless clearly needed. Same considerations as first trimester. |
| 3rd trimester | Avoid unless clearly needed. Same considerations as first trimester. |
Clinical note
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
| FDA category | Animal |
| Placental transfer | Limited data; however, systemic absorption from topical/otic use is minimal, so placental transfer is expected to be negligible. Parenteral neomycin crosses placenta but this formulation is not systemic. |
■ FDA Black Box Warning
None
| Common Effects | topical infections |
| Serious Effects |
Hypersensitivity to any componentPerforated tympanic membrane (for otic use)Mycobacterial or fungal infections of earViral infections of ear (e.g., herpes simplex, varicella)
| Precautions | Prolonged use may result in overgrowth of nonsusceptible organisms including fungi, If superinfection occurs, appropriate therapy should be initiated, Neomycin may cause ototoxicity and nephrotoxicity if absorbed systemically; caution in patients with impaired renal function, Use with caution in patients with a history of hypersensitivity to aminoglycosides or polymyxins, Ophthalmic use: do not use for viral or fungal infections; monitor intraocular pressure if used for >10 days, Otic use: not for use with perforated tympanic membrane or in patients with viral or fungal infections of the ear |
| Food/Dietary |
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| Breastfeeding |
| Systemic absorption from topical or otic use is negligible, making breastfeeding generally safe. However, avoid applying to breast area to prevent infant ingestion. Advise to apply after nursing and wipe off before next feeding if applied near breast. |
| Lactation Rating | L2: Probably Compatible |
| Teratogenic Risk | Neomycin and polymyxin B are aminoglycosides and polypeptide antibiotics, respectively, with minimal systemic absorption after topical/otic administration; hydrocortisone is a corticosteroid with low systemic bioavailability. Studies in pregnant animals for neomycin and polymyxin B are limited, but systemic aminoglycosides carry risk of fetal ototoxicity and nephrotoxicity, particularly in second and third trimesters. Hydrocortisone at topical doses is not associated with major malformations, but prolonged high-dose systemic corticosteroids may cause intrauterine growth restriction and adrenal suppression. The combination product is considered low risk for teratogenicity when used as directed topically or otic in pregnant women, but avoid prolonged use over large areas or broken skin. |
| Fetal Monitoring | No specific monitoring is required for topical/otic use. If used on extensive areas or damaged skin, monitor for signs of systemic toxicity (nephrotoxicity, ototoxicity, adrenal suppression). In pregnancy, assess fetal growth and amniotic fluid volume if prolonged high-dose corticosteroid exposure occurs. |
| Fertility Effects | No known adverse effects on fertility with topical/otic use. Systemic corticosteroids may affect menstrual cycles or sperm production, but this is unlikely with low bioavailability. |
| No significant food interactions. Avoid alcohol if dizziness is present. |
| Clinical Pearls | This combination is used topically for otic infections. Avoid use if tympanic membrane is perforated due to risk of ototoxicity (aminoglycoside component). Shake well before use. Use for no longer than 10 days. If no improvement, re-evaluate for fungal or resistant bacterial infection. |
| Patient Advice | Use only in the ear, not for eye or skin. · Shake the bottle well before each use. · Warm the bottle in hands for 1-2 minutes to avoid dizziness from cold drops. · Lie on your side with affected ear up, instill drops, and remain for 5 minutes. · Do not touch the dropper tip to any surface, including the ear. · Complete the full course even if symptoms improve. · Do not use if you have a perforated eardrum. · Contact your doctor if no improvement after 7-10 days or if rash, dizziness, or hearing loss occurs. |