NEOMYCIN AND POLYMYXIN B SULFATES AND HYDROCORTISONE
Clinical safety rating: safe
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
Neomycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, inhibiting bacterial protein synthesis. Polymyxin B is a cationic detergent 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.
| Metabolism | Neomycin: not significantly metabolized, excreted unchanged by kidneys. Polymyxin B: not significantly metabolized, excreted primarily by renal filtration. Hydrocortisone: metabolized in the liver via reduction and conjugation, primarily to tetrahydrocortisone and glucuronide conjugates. |
| Excretion | Neomycin: >90% unchanged in feces after oral administration; negligible renal excretion. Polymyxin B: 60% renal excretion of unchanged drug; remainder nonrenal. Hydrocortisone: primarily hepatic metabolism, <5% renal excretion unchanged. |
| Half-life | Neomycin: 2-3 hours (in adults with normal renal function); may accumulate in renal impairment. Polymyxin B: 6-8 hours (prolonged in renal impairment: up to 36 hours). Hydrocortisone: 1.2-1.5 hours (terminal). |
| Protein binding | Neomycin: negligible (0-10% bound). Polymyxin B: ~80-90% bound to albumin and other proteins. Hydrocortisone: ~90% bound to corticosteroid-binding globulin (CBG) and albumin. |
| Volume of Distribution | Neomycin: 0.25 L/kg (primarily extracellular fluid). Polymyxin B: 0.25-0.5 L/kg (distributes to tissues, limited CNS penetration). Hydrocortisone: 0.4 L/kg (distributes widely, including breast milk and placenta). |
| Bioavailability | Oral neomycin: <3% (poorly absorbed). Oral polymyxin B: negligible (<0.5%). Topical/ophthalmic/otic administration: minimal systemic absorption (<1% for polymyxin B and neomycin; hydrocortisone may be absorbed to a small degree but typically <1%). |
| Onset of Action | Topical otic: relief of inflammation and infection begins within 24-48 hours. Ophthalmic: clinical improvement within 2-3 days. Topical dermatologic: symptom relief within 48-72 hours. |
| Duration of Action | Topical otic/ophthalmic: effects persist for duration of treatment; no prolonged action after discontinuation. Duration is dependent on dosing frequency (typically 3-4 times daily). |
Instill 3 to 4 drops into the affected ear(s) 3 to 4 times daily. For otic suspension in adults.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No systemic absorption expected with otic use; no dose adjustment required. |
| Liver impairment | No systemic absorption expected with otic use; no dose adjustment required. |
| Pediatric use | Instill 3 drops into the affected ear(s) 3 times daily for children; dose similar to adult due to lack of systemic absorption. |
| Geriatric use | No specific adjustment; use same as adult dosing. Monitor for local irritation or hypersensitivity. |
| 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 | Neomycin and polymyxin B sulfates are minimally absorbed topically, and systemic levels are negligible; thus, transfer into breast milk is unlikely. Hydrocortisone is excreted in breast milk in small amounts, but topical application to limited areas is not expected to cause adverse effects in the infant. No M/P ratio is available. Use with caution, avoiding application to breast area. |
| Teratogenic Risk |
■ FDA Black Box Warning
None.
| Common Effects | topical infections |
| Serious Effects |
["Hypersensitivity to any component (neomycin, polymyxin B, hydrocortisone).","Fungal or viral infections of the ear (e.g., herpes simplex, varicella).","Perforated tympanic membrane (risk of ototoxicity)."]
| Precautions | ["Prolonged use may result in overgrowth of non-susceptible organisms including fungi.","Sensitization to neomycin may occur, especially with prolonged or repeated use.","Ototoxicity: neomycin is ototoxic when applied to open wounds or in patients with tympanic membrane perforation; avoid use in ears with perforated tympanic membranes.","Systemic absorption of corticosteroids may occur with prolonged use, leading to adrenal suppression.","Not for use in eyes (ophthalmic formulations differ)."] |
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| Neomycin and polymyxin B sulfates are poorly absorbed from intact skin, thus systemic exposure is minimal and teratogenic risk is low. Hydrocortisone is a corticosteroid; topical use in pregnancy is generally considered safe at low doses and short duration. However, prolonged use of high-potency corticosteroids may increase risk of orofacial clefts (first trimester) and fetal growth restriction (second/third trimester). The combination product is classified as Pregnancy Category C. Risk cannot be ruled out; use only if clearly needed. |
| Fetal Monitoring | Maternal: Monitor for signs of adrenal suppression if used extensively, especially on large areas or under occlusion. Fetal: No specific monitoring required for topical use; if used in large amounts or for prolonged periods, consider fetal growth ultrasound. |
| Fertility Effects | No known effects on fertility from topical neomycin, polymyxin B, or hydrocortisone. Systemic absorption is minimal. |