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 |
| Molecular Weight | 566.7 |
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 | Corticosteroids and aminoglycosides cross the placenta; risk of fetal harm not ruled out. Use only if potential benefit justifies potential risk. |
| 2nd trimester | Same as t1; possible risk of fetal nephrotoxicity and ototoxicity from tobramycin, and growth suppression from loteprednol etabonate. |
| 3rd trimester | Same as t2; prolonged use may increase risk of neonatal hypoglycemia and adrenal suppression. |
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 |
| Placental transfer | Both components cross the placenta; tobramycin reaches fetal serum levels approximately 50% of maternal levels. Loteprednol etabonate is assumed to cross, though data are limited. |
■ FDA Black Box Warning
None.
| Common Effects | Nephrotoxicity |
| Serious Effects |
Hypersensitivity to loteprednol etabonate, tobramycin, or any component of the formulationViral infections of the cornea (e.g., herpes simplex keratitis)Fungal infections of ocular structuresUntreated ocular bacterial infections
| 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. |
| Food/Dietary | No specific food interactions. Avoid alcohol due to potential corticosteroid interaction (not well studied locally). |
Loading safety data…
| Breastfeeding |
| Systemic absorption from ophthalmic use is low, but caution is advised. Tobramycin is excreted in breast milk in small amounts; loteprednol etabonate is minimally excreted. Monitor infant for diarrhea, candidiasis, or growth suppression. |
| Lactation Rating | L2 (Probably Compatible) |
| 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. |
| 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. |
| Clinical Pearls | Use only for ophthalmic conditions with concomitant bacterial infection and inflammation; avoid in viral or fungal infections. Shake well before each use. Do not touch dropper tip to any surface to avoid contamination. Monitor intraocular pressure if used >10 days. Contraindicated in epithelial herpes simplex keratitis (dendritic keratitis). |
| Patient Advice | Shake the bottle well before each use. · Do not touch the dropper tip to your eye or any surface to prevent contamination. · Remove contact lenses before instillation; may reinsert after 15 minutes. · Temporary blurred vision may occur; do not drive or operate machinery until clear. · Complete the full course even if symptoms improve; do not stop without consulting. · Report worsening redness, pain, vision changes, or discharge. · Avoid using other eye drops within 5 minutes of this medication. |