Tobramycin
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
- Tobramycin
Tobramycin: Exposure keratitis
One-Sentence Summary
Tobramycin is an aminoglycoside antibiotic originally used for bacterial infections, including meningitis, staphylococcal infections and several forms of conjunctivitis and uveitis. The TxGNN model predicts it may be effective for exposure keratitis, but there are no registered clinical trials and only 8 publications (mostly case reports and in vitro studies) that touch on this direction, 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 |
| Australia Market Status | Listed on the PBS Schedule (1 of 1 items) – TGA (ARTG) registration status is not included in this data |
| Number of PBS Items | 1 (valid: 1) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism of action data are not available for this report. Based on known information, tobramycin is a broad-spectrum aminoglycoside antibiotic with established activity against gram-negative bacteria such as Pseudomonas aeruginosa and against Staphylococcus aureus. Its efficacy in bacterial eye infections has been shown, and mechanistically it may be applicable to exposure keratitis.
Exposure keratitis occurs when the cornea is not adequately covered by the eyelids, so the surface dries and is damaged. This damaged surface is vulnerable to secondary bacterial infection. A topical antibiotic could therefore plausibly help prevent or treat that infection.
There are important caveats. The retrieved literature concerns infectious keratitis (contact lens-related, MRSA and Bacillus cereus) and in vitro corneal epithelial toxicity of aminoglycosides. It does not study exposure keratitis itself. The toxicity finding is a safety concern for an already compromised corneal surface.
Clinical Trial Evidence
Currently no related clinical trials registered for exposure keratitis.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 42842711 | 2026 | Retrospective cohort | Cornea | Compared outcomes of MRSA and MSSA S. aureus keratitis (infectious keratitis, not exposure keratitis) |
| 2707046 | 1989 | In vitro study | Current Eye Research | Compared corneal epithelial cell toxicity of neomycin, gentamicin, tobramycin and amikacin in rabbit cell culture |
| 17228760 | 2006 | In vitro study | Nippon Ganka Gakkai Zasshi | Compared MIC and post-antibiotic effect of eye drops against isolates from infectious keratitis in Japan |
| 42358321 | 2026 | In vitro study (veterinary) | Frontiers in Veterinary Science | Examined how fluorometholone changes antibiotic susceptibility of canine ocular pathogens |
| 11581057 | 2001 | Case report | Ophthalmology | Contact lens-associated Bacillus cereus keratitis |
| 34987857 | 2021 | Case report | Oxford Medical Case Reports | Multidrug-resistant Shewanella algae keratitis in a patient who could not 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 |
Australia Market Information
| ARTG Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| ARTG 10066T | TOBI Podhaler | Capsule containing powder for oral inhalation 28 mg (for use in Podhaler) | Not listed in the data compiled for this report |
The only registered Australian product is an inhaled formulation. There is no registered ophthalmic formulation in the data compiled for this report, so route compatibility with an eye indication is unconfirmed.
Safety Considerations
- Contraindications suggested by the knowledge graph (not label text): kidney disease, glaucoma and ocular hypertension, herpes simplex virus keratitis, viral, fungal and tuberculous eye infections, myasthenia gravis and other neuromuscular junction disease, Parkinson disease, diabetes and diabetic ketoacidosis, Clostridium difficile colitis, and perinatal necrotizing enterocolitis. Several of these eye-related entries are relevant to any ocular use.
- Corneal toxicity: in vitro data show aminoglycosides can be toxic to corneal epithelial cells, which is a particular concern when the corneal surface is already damaged, as in exposure keratitis.
- Drug interactions: 100 interactions were identified. Major interactions include magnesium sulfate and mannitol. Moderate interactions include other nephrotoxic or ototoxic agents (amphotericin B, vancomycin, kanamycin, neomycin), aspirin, mesalazine and related drugs, and several proton pump inhibitors (omeprazole, lansoprazole, pantoprazole, rabeprazole, dexlansoprazole).
Please also refer to the TGA-approved Product Information (PI) for full safety information, as label warnings were not available in the data compiled for this report.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction score is very high, but it is based on the model alone. There are no registered trials, the literature is indirect (infectious keratitis, in vitro toxicity and case reports), and the available data raise a safety concern for a compromised cornea. The only Australian product is an inhaled formulation.
To proceed, the following is needed:
- Mechanism of action data, to support the mechanistic-link analysis
- TGA Product Information warnings and contraindications, to complete safety screening
- Evidence from studies directly in exposure keratitis (for example, rates of secondary infection with and without prophylactic topical antibiotics)
- Assessment of corneal epithelial toxicity risk and comparison with other topical antibiotics
- Confirmation of an available ophthalmic formulation in Australia
Other Predicted Indications (for context)
| Rank | Predicted Indication | Score | Evidence Level | Comment |
|---|---|---|---|---|
| 3 | Otitis externa | 0.9981 | L4 | Best-supported of the other predictions: tobramycin is active against P. aeruginosa and S. aureus, with case reports in malignant otitis externa. Much of the literature is veterinary. There is an ototoxicity concern if the tympanic membrane is perforated. Suitable as a research question. |
| 5 | Post-bacterial disorder | 0.9979 | L5 | Two Phase 3 open-label extension trials of tobramycin inhalation powder in cystic fibrosis (NCT01069705, NCT00982930), only indirectly relevant. |
| 7 | Infective urethral stricture | 0.9978 | L5 | One 1976 comparison with gentamicin in complicated urinary tract infection, which does not address stricture. |
| 10 | Epidemic keratoconjunctivitis | 0.9938 | L4 | Mainly adenoviral. Tobramycin has no antiviral activity and the literature is weak. |
| 2, 4, 6, 8, 9 | Non-human animal disease, postinfectious vasculitis, post-infectious syndrome, Chagas cardiomyopathy, infection-related haemolytic uraemic syndrome | 99.77–0.9983 | L5 | No trials or literature and no plausible mechanism. Aminoglycoside nephrotoxicity makes haemolytic uraemic syndrome particularly unfavourable. |
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.