NEODECADRON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEODECADRON (NEODECADRON).
Neomycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis. Dexamethasone is a potent corticosteroid with glucocorticoid and mineralocorticoid activity that binds to the glucocorticoid receptor, modulating gene expression to suppress inflammation and immune responses.
| Metabolism | Neomycin is minimally absorbed after topical application; absorbed fraction is primarily excreted unchanged by the kidneys. Dexamethasone is metabolized in the liver via CYP3A4 to inactive metabolites. |
| Excretion | Renal: ~70% as unchanged drug and metabolites; fecal/biliary: ~30% |
| Half-life | Terminal elimination half-life: 3-4 hours for neomycin; 6-8 hours for dexamethasone. Clinical context: Neomycin accumulates with renal impairment; dexamethasone has prolonged effects in hepatic dysfunction. |
| Protein binding | Dexamethasone: ~77% bound to albumin; neomycin: negligible binding (<10%) |
| Volume of Distribution | Dexamethasone: 0.5-0.8 L/kg (large Vd indicates extensive tissue distribution); neomycin: 0.2-0.3 L/kg (low Vd due to hydrophilicity) |
| Bioavailability | Oral: neomycin 1-3% (largely unabsorbed); dexamethasone 70-80%. IM dexamethasone: 80-100%; ophthalmic: minimal systemic absorption |
| Onset of Action | Ophthalmic solution: minutes to hours; topical: hours; IM dexamethasone: 1-2 hours |
| Duration of Action | Ophthalmic: 4-6 hours; topical: 6-12 hours; IM dexamethasone: 12-36 hours |
| Molecular Weight | Dexamethasone: 392.46 Da; Neomycin sulfate: 908.9 Da (neomycin B); Polymyxin B sulfate: 1301.6 Da (polymyxin B1). For the combination, the active components have varying molecular weights, but the primary concern for placental transfer is dexamethasone. |
1-2 drops into conjunctival sac every 1-2 hours during the day and every 2-4 hours at night for severe conditions; for mild conditions, 1-2 drops 4-6 times daily. Ophthalmic suspension.
| Dosage form | OINTMENT |
| Renal impairment | No dose adjustment required for topical ophthalmic use; systemic absorption negligible. |
| Liver impairment | No dose adjustment required for topical ophthalmic use; systemic absorption negligible. |
| Pediatric use | Not recommended for pediatric use due to potential systemic effects; safety and efficacy not established. |
| Geriatric use | Use with caution due to increased risk of intraocular pressure elevation and cataract formation; monitor intraocular pressure regularly. |
| 1st trimester | Avoid use; first trimester exposure associated with increased risk of oral clefts (odds ratio 3-6) and possibly other malformations. Corticosteroids cross placenta. Fetal growth restriction reported. |
| 2nd trimester | Use only if potential benefit outweighs risk. Risk of fetal growth restriction, hypothalamic-pituitary-adrenal suppression, and possible neurodevelopmental effects. Monitor fetal growth. |
| 3rd trimester | Use only if clearly needed. Prolonged use may cause fetal adrenal suppression, neonatal hypoglycemia, and growth restriction. Avoid high doses near term. |
Clinical note
Comprehensive clinical and safety monograph for NEODECADRON (NEODECADRON).
| Placental transfer | Dexamethasone readily crosses the placenta (fetal concentration ~30-40% of maternal). Neomycin and polymyxin B cross to a minimal extent due to their high molecular weight and polar nature. However, dexamethasone is the primary concern. |
| Breastfeeding |
■ FDA Black Box Warning
None (FDA label does not include a black box warning). However, aminoglycosides carry risks of nephrotoxicity and ototoxicity with systemic absorption.
| Serious Effects |
Hypersensitivity to any component (neomycin, polymyxin B, dexamethasone)Systemic fungal infections (unless used with appropriate antifungal therapy)Intracranial hypertension (pseudotumor cerebri) due to corticosteroid useAdministration of live or live-attenuated vaccines during therapy (corticosteroid immunosuppression)Active untreated infections (systemic or localized) except when used as adjunctive therapyKnown ocular herpes simplex (opthalmic preparations) – not directly applicable, but systemic use is relative; for ophthalmic: epithelial herpes simplex keratitis
| Precautions | Prolonged use may lead to suppression of adrenal function, cataracts, glaucoma, or secondary infections including fungal overgrowth. Neomycin may cause hypersensitivity reactions including contact dermatitis. Systemic absorption may occur with extensive application, especially on broken skin, leading to nephrotoxicity and ototoxicity. Use with caution in patients with renal impairment. |
| Food/Dietary |
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| Neomycin, polymyxin B, and dexamethasone are excreted into breast milk in low amounts. However, due to the potential for neonatal immunosuppression, growth suppression, and interference with endogenous corticosteroid production, caution is advised. Use only when clearly indicated and monitor infant for adverse effects. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | Category C: Corticosteroids cross placenta. First trimester: Increased risk of cleft palate (OR 1.3-3.4). Second/third trimester: Fetal adrenal suppression, intrauterine growth restriction, oligohydramnios with prolonged use. |
| Fetal Monitoring | Monitor maternal blood pressure, blood glucose, fluid/electrolytes. Fetal ultrasound for growth restriction, amniotic fluid volume, and adrenal suppression signs. |
| Fertility Effects | No direct evidence of fertility impairment; high-dose corticosteroids may suppress hypothalamic-pituitary-adrenal axis, potentially affecting ovulation. |
| No clinically significant food interactions. No dietary restrictions required. |
| Clinical Pearls | NEODECADRON (neomycin + dexamethasone) is an ophthalmic suspension used for corticosteroid-responsive ocular conditions with bacterial infection or risk. Do not use for viral (e.g., herpes simplex) or fungal infections. Monitor intraocular pressure if used >10 days. Shake well before use. Avoid prolonged use to prevent secondary infections. Contact lens wearers should remove lenses before instillation and wait 15 minutes before reinserting. |
| Patient Advice | Shake the bottle vigorously before each use. · Do not touch the dropper tip to any surface to avoid contamination. · Remove contact lenses before using; wait at least 15 minutes before reinserting. · Contact your doctor if symptoms worsen or do not improve after 2-3 days. · Do not use this medication for longer than prescribed; prolonged use can increase eye pressure or cause cataracts. · If you have glaucoma, cataracts, or diabetes, inform your doctor before use. · Avoid driving or operating machinery if your vision is blurred after instillation. |