Tobramycin
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Tobramycin: From Bacterial Infections to Exposure Keratitis
One-Sentence Summary
Tobramycin is an aminoglycoside antibiotic internationally used to treat serious Gram-negative bacterial infections (notably Pseudomonas aeruginosa), including pulmonary infections in cystic fibrosis and external eye infections. The TxGNN model predicts it may be effective for Exposure Keratitis, but this direction is currently supported only by 2 clinical trials (neither directly testing tobramycin) and 7 publications, none of which evaluate tobramycin specifically in this condition.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not documented in this dataset; internationally tobramycin is used for Gram-negative bacterial infections (e.g. Pseudomonas aeruginosa, cystic fibrosis pulmonary infection, external eye infections) |
| Predicted New Indication | Exposure Keratitis |
| TxGNN Prediction Score | 99.93% |
| Evidence Level | L4 |
| UK Market Status | Not marketed |
| Number of Marketing Authorisations | 0 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available. Based on known pharmacology, tobramycin is an aminoglycoside antibiotic active against common secondary pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa, and ophthalmic tobramycin formulations are already used for bacterial external eye infections.
Exposure keratitis, however, is fundamentally a mechanical/exposure-related corneal condition — typically caused by inadequate eyelid closure — rather than a primary bacterial disease. Antibiotics such as tobramycin could only address a secondary bacterial complication of exposure keratitis; they do not treat the underlying cause (eyelid closure failure, corneal exposure, tear film deficiency).
The two clinical trials linked to this prediction (NCT05313828, NCT06200727) do not test tobramycin as the intervention: one concerns dendritic (herpetic) corneal ulcers, and the other evaluates a platelet-rich fibrin membrane. The supporting literature is similarly indirect — mostly case reports of unrelated keratitis pathogens and an in vitro corneal toxicity study of aminoglycosides. Overall, the mechanistic rationale is plausible only as adjunctive management of secondary infection, not as a primary treatment for exposure keratitis itself.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrolment | Key Findings |
|---|---|---|---|---|
| NCT05313828 | N/A | Unknown | 40 | Compares treatment modalities for dendritic (herpetic) corneal ulcer; tobramycin is not the study intervention (relevance grade C) |
| NCT06200727 | N/A | Unknown | 170 | Evaluates platelet-rich fibrin (PRF) membrane for ophthalmic conditions including corneal ulcer; no direct link to tobramycin (relevance grade C) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 34987857 | 2021 | Case report | Oxford Medical Case Reports | Bacterial keratitis caused by multidrug-resistant Shewanella algae in a patient unable to close his eyes voluntarily (exposure-related) |
| 11581057 | 2001 | Case report | Ophthalmology | Bacillus cereus keratitis associated with contact lens wear |
| 2707046 | 1989 | In vitro | Current Eye Research | Cytotoxicity of four aminoglycosides (including tobramycin) on rabbit corneal epithelial cells |
| 33847093 | 2021 | Case series (veterinary) | Polish Journal of Veterinary Sciences | Feline ocular toxoplasmosis — not relevant to tobramycin or exposure keratitis |
| 12861116 | 2003 | Case report | Eye & Contact Lens | Bilateral MRSA keratitis following photorefractive keratectomy |
| 17228760 | 2006 | In vitro/PK | Nippon Ganka Gakkai Zasshi | Minimum inhibitory concentration and postantibiotic effect of antibiotic eye drops against keratitis isolates in Japan |
| 14574976 | 2003 | Case report | Yan Ke Xue Bao (Eye Science) | Paracentral corneal dellen in Graves ophthalmopathy — unrelated aetiology |
UK Market Information
Tobramycin has no marketing authorisation currently recorded for the UK in this dataset (0 licenses; market status: Not marketed).
Safety Considerations
Please refer to the SmPC and BNF for safety information. Report suspected adverse reactions via the Yellow Card Scheme.
Note: A blocking data gap has been identified — MHRA/manufacturer warnings and contraindications for tobramycin are not yet available in this evaluation, which prevents completion of the initial safety review (S1 stage).
Conclusion and Next Steps
Decision: Hold
Rationale: The evidence for tobramycin in exposure keratitis is weak — neither of the two linked clinical trials tests tobramycin directly, and the literature consists largely of unrelated case reports and an in vitro toxicity study. Combined with the absence of UK marketing authorisation and a blocking data gap on safety warnings/contraindications, this candidate does not currently meet the bar to proceed.
To proceed, the following is needed:
- Detailed mechanism of action (MOA) data for tobramycin
- MHRA/SmPC warnings, contraindications and DDI data (currently a blocking data gap)
- Clinical trials or studies that directly evaluate tobramycin’s efficacy in exposure keratitis, rather than in unrelated corneal conditions
- Clarification of UK market status/import pathway, given no marketing authorisation is currently recorded
Note: Within the same evidence pack, otitis externa (rank 3) shows substantially stronger and more directly relevant evidence — an L3 evidence level with multiple tobramycin-specific cohort and case-series studies, including long-term safety data — and is scored “Proceed with Guardrails.” This may be a more promising repurposing candidate for further evaluation than exposure keratitis.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.