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). |
| Molecular Weight | 1 |
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 | Topical use appears safe; systemic absorption minimal but may cause fetal ototoxicity or nephrotoxicity if large areas are treated. Avoid prolonged use. |
| 2nd trimester | Same as T1; caution with extensive application or prolonged therapy. |
| 3rd trimester | Same as T1; potential for fetal ototoxicity and nephrotoxicity if significant systemic absorption occurs. |
Clinical note
Other nephrotoxic or ototoxic drugs increase risk of toxicity Can cause ototoxicity and nephrotoxicity with systemic use.
| FDA category | Animal |
| Placental transfer | Neomycin and polymyxin B cross the placenta to a limited extent due to high molecular weight and poor lipid solubility; hydrocortisone crosses minimally. Significant systemic absorption only occurs with large topical doses or compromised skin. |
■ FDA Black Box Warning
None.
| Common Effects | topical infections |
| Serious Effects |
Hypersensitivity to neomycin, polymyxin B, hydrocortisone, or any componentPerforated tympanic membrane (for otic preparations)Fungal or viral infections (e.g., herpes simplex, varicella) at the application site
| 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). |
| Food/Dietary |
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| Breastfeeding |
| Topical application likely to result in negligible systemic levels; however, avoid application to breast or large areas to minimize infant exposure. Oral absorption in infants is poor, but diarrhea or candidiasis could theoretically occur. |
| Lactation Rating | L2 (Probably Safe - Limited Data) |
| Teratogenic Risk | 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. |
| No known food interactions. Avoid alcohol as it may worsen dizziness or side effects. |
| Clinical Pearls | This combination product (neomycin, polymyxin B, hydrocortisone) is an otic suspension used for bacterial otitis externa with inflammation. Neomycin is an aminoglycoside with good activity against Gram-negative rods; polymyxin B covers Gram-negative rods including Pseudomonas; hydrocortisone reduces inflammation. Avoid use in patients with tympanic membrane perforation due to risk of ototoxicity from neomycin. Shake well before use. For optimal contact, patient should lie on side with affected ear up for 5 minutes after instillation. |
| Patient Advice | Use exactly as prescribed; do not stop early even if symptoms improve. · Shake the bottle well before each use. · Lie down with the affected ear upward for at least 5 minutes after applying drops. · Do not touch the dropper tip to the ear or any surface to avoid contamination. · Contact your doctor if you experience ringing in the ears, hearing loss, or dizziness. · Do not use if you have a perforated eardrum or if ear discharge is present without consulting a doctor. · Avoid swimming or getting water in the ear during treatment. |