Neomycin
| Evidence Level: L3 | Predicted Indications: 10 |
Table of Contents
Neomycin: From Topical and Gut-Luminal Antibacterial Use to Irritable Bowel Syndrome
One-Sentence Summary
Neomycin is a poorly absorbed aminoglycoside antibiotic, marketed in Singapore mainly in topical, eye/ear and vaginal products. The TxGNN model predicts it may be effective for irritable bowel syndrome (IBS), with 1 clinical trial and 14 publications currently supporting this direction. The evidence is small and mostly observational or review-level.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not specified in the Singapore registration data (indication text is blank for all licences) |
| Predicted New Indication | Irritable bowel syndrome |
| TxGNN Prediction Score | 98.55% |
| Evidence Level | L3 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 9 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available. Based on known information, neomycin is an aminoglycoside antibiotic that is poorly absorbed and acts mainly in the gut lumen when taken orally. In the registered products it is mostly combined with other agents, such as corticosteroids or polymyxin B, and applied topically or to the eye or ear.
The proposed link to IBS runs through the gut microbiome. Neomycin may reduce methane-producing microbes and small intestinal bacterial overgrowth (SIBO), both of which have been associated with IBS, especially constipation-predominant IBS (C-IBS). Published work on neomycin combined with rifaximin supports this idea. In methane-positive patients, a combination of the two appeared more effective than either alone.
Note that the registered Singapore products are topical, ophthalmic, otic and vaginal. None is an oral formulation for gut use, so the route needed for IBS is not currently available locally.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00945334 | Not specified (NA) | Completed | 37 | Double-blind, placebo-controlled trial comparing neomycin with rifaximin plus neomycin in methane-positive patients with constipation-predominant IBS |
The trial is small and its phase is not specified, so it cannot support a higher evidence level.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 12591062 | 2003 | Double-blind RCT | Am J Gastroenterol | Antibiotic treatment that normalised lactulose breath test results correlated with IBS symptom improvement |
| 16832617 | 2006 | RCT subanalysis | Dig Dis Sci | Neomycin improved constipation in C-IBS, dependent on the presence of methane |
| 19996983 | 2010 | Clinical study | J Clin Gastroenterol | Rifaximin plus neomycin was most effective in IBS patients with methane on breath testing |
| 24788320 | 2014 | Clinical study | Dig Dis Sci | Antibiotic treatment of C-IBS, comparing neomycin with rifaximin plus neomycin in methane-positive subjects |
| 40240267 | 2025 | Cohort | Rev Gastroenterol Mex | Compared three antibiotic regimens for SIBO in IBS patients, including symptom response and eradication |
| 22298980 | 2011 | Review | Gastroenterol Hepatol | Role of gut flora and antibiotics in IBS |
| 24666019 | 2014 | Review | Curr Med Res Opin | Probiotics and antimicrobials in IBS management |
| 31363445 | 2019 | Review | Cureus | Methane and constipation-predominant IBS |
| 26819502 | 2016 | Review | World J Gastroenterol | Hypothesis that infectious mechanisms may underlie IBS |
| 38700306 | 2023 | Review | J Assoc Physicians India | Dysbiosis in IBS |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN04129P | NEO-BETASONE CREAM | Cream | Not stated |
| SIN04113P | NEO-CORTISONE CREAM | Cream | Not stated |
| SIN00678P | BANEOCIN POWDER | Powder | Not stated |
| SIN01930P | UNIFLEX-N CREAM | Cream | Not stated |
| SIN00959P | DEXTRACIN EYE/EAR DROPS | Solution | Not stated |
Nine valid single-ingredient registrations exist in total. The other four are POLYGYNAX VAGINAL CAPSULE, MAXITROL STERILE OPHTHALMIC SUSPENSION, POLYDEXA EAR DROPS and POLYBAMYCIN OINT.
Safety Considerations
- Drug Interactions: The interaction screening found 100 potential interactions. Major-level examples include botulinum toxin type A, intravenous human immunoglobulin G, bacitracin, bumetanide and capreomycin. Moderate-level examples include amikacin, amphotericin B, omeprazole, rabeprazole, mesalazine, alendronic acid and estradiol.
- Contact allergy: Literature compiled for related indications identifies neomycin as a frequent contact allergen. It can cause allergic contact dermatitis, with cross-sensitivity to tobramycin.
Please refer to the package insert for warnings and contraindications.
Conclusion and Next Steps
Decision: Hold
Rationale: The IBS prediction is the best-supported of the ten predicted indications, with a completed placebo-controlled trial and several clinical studies in methane-positive C-IBS. However, the trial is small (n=37) with no specified phase, the rest of the evidence is observational or review-level, and no oral gut-directed neomycin product is registered in Singapore. Package insert safety data is also missing.
To proceed, the following is needed:
- Package insert warnings and contraindications from the HSA, since safety screening cannot proceed without them
- Mechanism of action data from DrugBank
- A larger, well-designed Phase 2/3 trial in a defined IBS subgroup (such as methane-positive C-IBS)
- Assessment of an oral, minimally absorbed formulation and its availability in Singapore
- A safety plan covering aminoglycoside risks with repeated oral courses, and interactions with other nephrotoxic or ototoxic drugs
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.