MAXITROL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MAXITROL (MAXITROL).
Maxitrol is a combination of dexamethasone (corticosteroid), neomycin (aminoglycoside antibiotic), and polymyxin B (polymyxin antibiotic). Dexamethasone suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis. Neomycin binds to bacterial 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis. Polymyxin B disrupts bacterial cell membrane integrity by binding to lipopolysaccharides.
| Metabolism | Dexamethasone undergoes hepatic metabolism primarily via CYP3A4. Neomycin is not metabolized; excreted unchanged in urine. Polymyxin B is not significantly metabolized; mainly renally excreted. |
| Excretion | Renal: neomycin 30–50%; polymyxin B <1%; dexamethasone <1%. Fecal: neomycin >50% (unabsorbed); polymyxin B >99% (unabsorbed); dexamethasone <5%. Biliary: negligible for all components. |
| Half-life | Neomycin: 2–3 h (topical) but prolonged in renal impairment. Polymyxin B: 6–7 h (topical). Dexamethasone: 3–4 h (topical). Clinical: systemic absorption minimal with intact epithelium; half-life may be prolonged with corneal abrasion or inflammation. |
| Protein binding | Neomycin: <30% bound to serum proteins. Polymyxin B: ~80% bound (primarily to albumin). Dexamethasone: ~77% bound (to albumin and corticosteroid-binding globulin). |
| Volume of Distribution | Neomycin: 0.25–0.4 L/kg (topical, minimal systemic). Polymyxin B: ~0.1–0.2 L/kg (topical). Dexamethasone: ~0.8–1.0 L/kg (topical). Clinical: Vd reflects negligible systemic distribution; drug remains primarily in ocular tissues. |
| Bioavailability | Ophthalmic: <5% systemic absorption via corneal and conjunctival routes. Intact epithelium limits absorption; inflamed or abraded cornea may increase systemic absorption modestly. Oral/IM: not applicable for ophthalmic formulation. |
| Onset of Action | Ophthalmic: anti-inflammatory and antibacterial effects typically within 30–60 min after instillation. Clinical improvement in signs/symptoms often within 24–48 h. |
| Duration of Action | Antibacterial: duration of bactericidal effect on ocular surface approximately 4–6 h after a single dose. Anti-inflammatory: dexamethasone duration of action 4–8 h; requires q4–6h dosing for sustained effect. |
1-2 drops or 0.5-1 inch strip of ointment into the conjunctival sac every 4-6 hours; in severe cases, every 2-4 hours. Frequency may be reduced after improvement.
| Dosage form | OINTMENT |
| Renal impairment | No systemic absorption expected with topical ophthalmic use; no dose adjustment required. |
| Liver impairment | No systemic absorption expected with topical ophthalmic use; no dose adjustment required. |
| Pediatric use | Safety and efficacy not established in pediatric patients; use only if clearly needed. |
| Geriatric use | Same as adult dosing; monitor intraocular pressure and cataract formation closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MAXITROL (MAXITROL).
| Breastfeeding | Systemic absorption of Maxitrol components is negligible after ophthalmic use. Dexamethasone is excreted in breast milk in small amounts; M/P ratio not established. Neomycin and polymyxin B are poorly absorbed orally, so infant exposure via breast milk is minimal. Considered compatible with breastfeeding with caution; monitor infant for diarrhea, rash, or candidiasis. |
| Teratogenic Risk | Maxitrol (neomycin, polymyxin B, dexamethasone) ophthalmic: Topical use has minimal systemic absorption. Dexamethasone is a corticosteroid; systemic corticosteroids in first trimester are associated with cleft palate (risk increase ~0.1-0.3%). No specific human data for ophthalmic route. Neomycin and polymyxin B are not absorbed systemically in significant amounts. Overall, risk is low with ophthalmic use, but avoid during pregnancy if possible. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to any component","Untreated viral infections (e.g., herpes simplex keratitis)","Fungal or mycobacterial ocular infections"]
| Precautions | ["Prolonged use may lead to ocular hypertension/glaucoma, cataract formation, secondary infections, and delayed wound healing.","Neomycin may cause dose-related nephrotoxicity and ototoxicity, especially in patients with renal impairment or prolonged use.","Polymyxin B can cause neurotoxicity and nephrotoxicity.","Avoid prolonged use in children due to risk of adrenal suppression."] |
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| Fetal Monitoring | No specific monitoring required for ophthalmic use. For prolonged or high-dose use, monitor maternal intraocular pressure and fetal growth if systemic effects concern. Evaluate for signs of adrenal suppression in newborn if used near term with high doses. |
| Fertility Effects | No known adverse effects on fertility with ophthalmic use. Topical corticosteroids, aminoglycosides, and polymyxins have not been associated with impaired fertility in humans. |