NEOMYCIN SULFATE-DEXAMETHASONE SODIUM PHOSPHATE
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, causing misreading of mRNA and inhibiting bacterial protein synthesis. Dexamethasone is a corticosteroid that induces phospholipase A2 inhibitory proteins, thereby suppressing prostaglandin and leukotriene synthesis, reducing inflammation.
| Metabolism | Neomycin is minimally absorbed and excreted unchanged in urine. Dexamethasone is hepatically metabolized via CYP3A4. |
| Excretion | Neomycin is primarily excreted unchanged in feces (~97%) after oral administration, with about 1% absorbed and renally excreted. Dexamethasone is metabolized in liver and excreted renally (~65% as metabolites, 2-5% unchanged) and in feces (~20%). |
| Half-life | Neomycin: terminal half-life ~2-3 hours after oral absorption (negligible systemic absorption); in renal impairment, half-life can extend to 12-24 hours. Dexamethasone: terminal half-life ~36-54 hours (mean ~48 hours) in adults. |
| Protein binding | Neomycin: negligible protein binding (<10%). Dexamethasone: ~77% bound primarily to albumin. |
| Volume of Distribution | Neomycin: Vd ~0.1-0.2 L/kg (confined to extracellular fluid due to hydrophilic nature). Dexamethasone: Vd ~0.5-0.8 L/kg, indicating wide distribution including intracellular and central nervous system. |
| Bioavailability | Neomycin: oral bioavailability <3% (nearly negligible systemic absorption). Dexamethasone sodium phosphate: oral bioavailability ~80-90% (as dexamethasone); IV and ophthalmic administration yield 100% systemic availability for the absorbed fraction, though ophthalmic dose is negligible systemically. For the combination product, systemic absorption from ophthalmic drops is minimal. |
| Onset of Action | Neomycin oral: onset within 1-2 hours for bowel sterilization; ophthalmic drops: rapid (minutes) for anti-infective effect. Dexamethasone sodium phosphate: IV onset immediate (minutes); ophthalmic drops: onset within 1-2 hours for anti-inflammatory effect. |
| Duration of Action | Neomycin oral: duration ~6-8 hours for bowel sterilization; ophthalmic: duration ~4-6 hours. Dexamethasone: IV duration ~12-36 hours for anti-inflammatory effect (dose-dependent); ophthalmic: duration ~6-8 hours. |
Ophthalmic: 1-2 drops of the solution or small amount of the ointment (approximately 1/2 inch into the conjunctival sac) every 3-4 hours, or more frequently if needed. Otic: 4 drops into the affected ear 3-4 times daily.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No specific dose adjustment guidelines available for ophthalmic/otic use; systemic absorption is minimal, but caution in severe renal impairment if used on large denuded areas. |
| Liver impairment | No specific dose adjustment guidelines available for ophthalmic/otic use; systemic absorption is minimal, and hepatic impairment is unlikely to affect topical dosing. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established for ophthalmic or otic use; use only if clearly needed and with caution, dosing similar to adults but adjusted by severity and response. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to increased risk of adverse effects from systemic absorption if applied to large areas or broken 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 | Topical/ophthalmic use: Minimal systemic absorption; compatible with breastfeeding. Systemic use: Corticosteroids excreted in breast milk; neonatal adrenal suppression possible. Aminoglycosides poorly excreted; M/P ratio not established. Avoid application to breast area to prevent infant ingestion. |
| Teratogenic Risk |
■ FDA Black Box Warning
Neomycin sulfate can cause nephrotoxicity and ototoxicity, even with ophthalmic use, especially in patients with renal impairment or prolonged use. Risk is dose- and duration-dependent.
| Common Effects | topical infections |
| Serious Effects |
["Hypersensitivity to neomycin, dexamethasone, or any component.","Fungal, viral (e.g., herpes simplex keratitis, vaccinia, varicella), or mycobacterial ocular infections.","Untreated purulent infections of the eye.","Children under 2 years of age (safety not established)."]
| Precautions | ["Prolonged use may lead to secondary infections (fungal, resistant bacteria).","Neomycin: nephrotoxicity, ototoxicity (including vestibular and cochlear damage), especially with accumulation in renal impairment.","Dexamethasone: adrenal suppression, increased intraocular pressure, cataract formation, delayed wound healing.","Hypersensitivity reactions to neomycin or cross-sensitivity to other aminoglycosides.","Use with caution in patients with glaucoma, diabetes, or tuberculosis."] |
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| Pregnancy Category D. First trimester: Corticosteroid use associated with cleft palate (2-3 fold increased risk). Aminoglycosides may cause fetal ototoxicity but risk is low with topical/ophthalmic use. Second and third trimesters: Potential for fetal adrenal suppression with prolonged maternal corticosteroid use. Avoid systemic use if possible. |
| Fetal Monitoring | Monitor maternal blood glucose (corticosteroid-induced hyperglycemia). Assess fetal growth and amniotic fluid index with prolonged use. In cases of systemic absorption (e.g., extensive skin breakdown), monitor audiometry and renal function for aminoglycoside toxicity. |
| Fertility Effects | No known direct effect on fertility. High-dose corticosteroids may disrupt menstrual cycles, potentially affecting ovulation. Aminoglycosides not associated with fertility impairment. |