Tobramycin
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Tobramycin: Exposure keratitis
One-Sentence Summary
Tobramycin is an aminoglycoside antibiotic, originally used for bacterial infections such as staphylococcal infection, conjunctivitis, and uveitis-related eye conditions. The TxGNN model predicts it may be effective for exposure keratitis, but no clinical trials and only 8 publications (none on exposure keratitis itself) are available, so the evidence is weak.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not recorded in the local data |
| Predicted New Indication | Exposure keratitis |
| TxGNN Prediction Score | 0.9993 |
| Evidence Level | L4 |
| Canada Market Status | Marketed (marketed DINs: 14 of 14) |
| Number of DINs | 14 (marketed: 14) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on known information, tobramycin is a broad-spectrum aminoglycoside that inhibits bacterial protein synthesis. It is already used topically for ocular bacterial infections, and its efficacy in those infections is established.
Exposure keratitis occurs when the cornea is not adequately protected (for example, when the eyelids cannot close), leaving it dry and vulnerable to secondary bacterial infection. A topical antibacterial could therefore plausibly help prevent or treat that infection.
The caveat is that none of the retrieved literature addresses exposure keratitis directly. It covers bacterial keratitis in general and in vitro data. One in vitro study also found that aminoglycosides, including tobramycin, are toxic to corneal epithelial cells, which is a concern for an already compromised corneal surface.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 42842711 | 2026 | Retrospective cohort | Cornea | Compares clinical features, susceptibility, treatment, and outcomes of MRSA and MSSA S. aureus keratitis |
| 2707046 | 1989 | In vitro study | Current Eye Research | Aminoglycosides (neomycin, gentamicin, tobramycin, amikacin) showed cytotoxicity in rabbit corneal epithelial cell cultures |
| 17228760 | 2006 | In vitro study | Nippon Ganka Gakkai Zasshi | MIC and post-antibiotic effect of eyedrops against isolates from infectious keratitis in Japan |
| 42358321 | 2026 | In vitro study (veterinary) | Frontiers in Veterinary Science | Effect of fluorometholone on antibiotic susceptibility of canine ocular pathogens |
| 11581057 | 2001 | Case report | Ophthalmology | Bacillus cereus keratitis associated with contact lens wear |
| 34987857 | 2021 | Case report | Oxford Medical Case Reports | Multidrug-resistant Shewanella algae keratitis in a patient unable to close his eyes |
| 12861116 | 2003 | Case report | Eye & Contact Lens | Bilateral MRSA keratitis after photorefractive keratectomy |
| 14574976 | 2003 | Case report | Yan Ke Xue Bao | Paracentral corneal dellen as a rare sign of Graves ophthalmopathy |
Canada Market Information
Fourteen valid licences are listed in Canada. Dosage form, manufacturer, and approved-indication text are not available for any of them, so the table shows only the DIN and product name.
| DIN | Product Name |
|---|---|
| 02230640 | Tobramycin Injection |
| 02239630 | TOBI |
| 02533103 | Tobramycin Injection USP |
| 00513962 | TOBREX |
| 02241209 | Tobramycin Injection USP |
Other listed products include TOBI PODHALER, TOBRADEX (two DINs), TOBREX (a second DIN), Teva-Tobramycin, Sandoz Tobramycin, Tobramycin for Injection, and additional Tobramycin Injection USP licences.
Safety Considerations
- Contraindications (from the TxGNN knowledge graph, not label text): kidney disease, myasthenia gravis and other neuromuscular junction disorders, Parkinson disease and parkinsonian disorders, herpes simplex virus keratitis, viral, fungal, and tuberculous eye infections, ophthalmic herpes zoster, glaucoma and ocular hypertension, diabetes mellitus and diabetic ketoacidosis, hypercalcemia, nephrocalcinosis, Clostridium difficile colitis, perinatal necrotizing enterocolitis, and others. These should be confirmed against the Canadian product labelling.
- Drug Interactions: 100 interactions were identified. Major interactions are with magnesium sulfate and mannitol. Moderate interactions include other nephrotoxic or aminoglycoside agents (amphotericin B, vancomycin, kanamycin, neomycin), aspirin, and several proton pump inhibitors and aminosalicylates.
- Prediction-specific concern: in vitro corneal epithelial toxicity of aminoglycosides, which is relevant to a damaged cornea.
Package insert warnings and contraindications were not available for this report. Please refer to the Canadian package insert for the full safety information.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction score is very high, but there are no clinical trials and no study of exposure keratitis itself. The evidence is limited to general bacterial keratitis, case reports, and in vitro data, including a corneal epithelial toxicity signal. The case for this indication currently rests on model prediction and plausible mechanism alone.
To proceed, the following is needed:
- Health Canada package insert warnings and contraindications (a blocking gap for safety screening)
- Mechanism of action data
- Clinical data specific to exposure keratitis, such as the rate of secondary bacterial infection and comparison with other topical antibiotics
- Assessment of corneal epithelial toxicity risk in a compromised corneal surface
- Confirmation of the approved indications and dosage forms of the Canadian ophthalmic products (TOBREX, TOBRADEX)
Other Predicted Indications (Brief)
| Rank | Predicted Indication | Score | Evidence Level | Recommendation |
|---|---|---|---|---|
| 3 | Otitis externa | 0.9981 | L3 | Research Question |
| 10 | Epidemic keratoconjunctivitis | 0.9938 | L4 | Hold |
| 5 | Post-bacterial disorder | 0.9979 | L5 | Hold |
| 7 | Infective urethral stricture | 0.9978 | L5 | Hold |
Otitis externa has the most supporting literature of the alternatives. Pseudomonas aeruginosa and S. aureus, both within tobramycin’s spectrum, are common causes, and tobramycin has been used in malignant external otitis. Most of the literature is observational or veterinary, so it is indirect evidence, and ototoxicity is a concern if the tympanic membrane is not intact.
The remaining predictions (non-human animal disease, postinfectious vasculitis, post-infectious syndrome, Chagas cardiomyopathy, infection-related hemolytic uremic syndrome) have no trials or literature and are model predictions only (L5, Hold). Tobramycin’s nephrotoxicity is an additional concern for hemolytic uremic syndrome.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.