LOTEPREDNOL ETABONATE AND TOBRAMYCIN
Clinical safety rating: avoid
Other nephrotoxic or ototoxic drugs increase risk of toxicity Monitor peak and trough levels to minimize risk of nephrotoxicity and ototoxicity.
Loteprednol etabonate is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis; tobramycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, inhibiting bacterial protein synthesis.
| Metabolism | Loteprednol etabonate undergoes hydrolysis by esterases in the cornea and aqueous humor to inactive metabolites; tobramycin is primarily eliminated unchanged by renal glomerular filtration. |
| Excretion | Loteprednol etabonate: 75% renal, 20% fecal; Tobramycin: >90% renal as unchanged drug via glomerular filtration |
| Half-life | Loteprednol etabonate: ~2.8 hours (ocular); Tobramycin: ~2-3 hours (systemic, prolonged in renal impairment) |
| Protein binding | Loteprednol etabonate: ~70% bound to albumin; Tobramycin: <10% bound |
| Volume of Distribution | Loteprednol etabonate: ~1.6 L/kg; Tobramycin: ~0.26 L/kg (confined to extracellular fluid) |
| Bioavailability | Ophthalmic: low systemic absorption (loteprednol etabonate <1%; tobramycin <20% by topical ophthalmic route) |
| Onset of Action | Ophthalmic suspension: Loteprednol: within 24 hours; Tobramycin: within 12 hours |
| Duration of Action | Loteprednol: anti-inflammatory effect lasts 4-6 hours; Tobramycin: antibacterial effect persists up to 12 hours |
1-2 drops into affected eye(s) every 4-6 hours; in severe cases, may be given every 1-2 hours initially.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | 1 drop into affected eye(s) every 4-6 hours; safety and efficacy in children <2 years not established. |
| Geriatric use | No specific dose adjustment; use same dosing as adults with monitoring for increased intraocular pressure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other nephrotoxic or ototoxic drugs increase risk of toxicity Monitor peak and trough levels to minimize risk of nephrotoxicity and ototoxicity.
| FDA category | Positive |
| Breastfeeding | Unknown if loteprednol or tobramycin excreted in breast milk. Tobramycin has low oral bioavailability, so infant exposure likely minimal. M/P ratio not available. Use with caution; consider delaying breastfeeding until 4 hours after last dose. |
| Teratogenic Risk | Corticosteroids are associated with increased risk of cleft palate in first trimester. Limited human data for loteprednol; animal studies show fetal loss and malformations at high doses. Tobramycin aminoglycoside risk: potential for ototoxicity in second and third trimesters due to fetal eighth cranial nerve damage. Avoid use unless benefit outweighs risk. |
■ FDA Black Box Warning
None.
| Common Effects | Nephrotoxicity |
| Serious Effects |
["Hypersensitivity to loteprednol etabonate, tobramycin, or any component of the formulation.","Epithelial herpes simplex keratitis (dendritic keratitis).","Viral diseases of the cornea and conjunctiva (e.g., vaccinia, varicella).","Mycobacterial infections of the eye.","Fungal diseases of ocular structures."]
| Precautions | ["Prolonged use may lead to ocular hypertension/glaucoma, cataract formation, secondary infections, and delayed wound healing.","Prolonged use may result in fungal or viral superinfection or overgrowth of non-susceptible bacteria.","Systemic absorption may occur; caution in patients with known or suspected existing glaucoma or steroid responders.","Not for injection into the eye."] |
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| Fetal Monitoring | Monitor maternal renal function and hearing if prolonged use. Fetal ultrasonography for growth and anatomy. Assess for neonatal ototoxicity if used near term. |
| Fertility Effects | No known fertility effects in humans. Animal studies with corticosteroids show reduced fertility at high doses. |