Chloramphenicol
| Evidence Level: L3 | Predicted Indications: 10 |
Table of Contents
Chloramphenicol: From Typhoid Fever to Conjunctivitis
One-Sentence Summary
Chloramphenicol is a broad-spectrum antibiotic originally used for systemic bacterial and rickettsial infections such as typhoid fever, meningitis and typhus. The TxGNN model predicts it may be effective for conjunctivitis, with no registered clinical trials and 20 publications (mostly reviews and older comparative studies) currently supporting this direction. Topical chloramphenicol for bacterial conjunctivitis is already established clinical practice in some countries, so this is closer to an existing use than true repurposing.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Typhoid fever, salmonellosis, paratyphoid fever, meningococcal infection, streptococcal meningitis, and other infections (the Singapore licence records contain no indication text) |
| Predicted New Indication | Conjunctivitis |
| TxGNN Prediction Score | 99.66% |
| Evidence Level | L3 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 3 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on known pharmacology, chloramphenicol is a broad-spectrum, bacteriostatic antibiotic that inhibits bacterial protein synthesis by binding the 50S ribosomal subunit.
Its original indications are bacterial and rickettsial infections, including several that involve mucosal and ear/skin sites (otitis externa, skin infections). Bacterial conjunctivitis is a superficial infection of the eye, so the same antibacterial activity is directly relevant. The supplied literature notes that topical chloramphenicol is widely used for conjunctivitis in the UK, though rarely prescribed for it in the U.S.
The Singapore registrations are for ear drops and an eye drop product (0.5%), which means a topical ocular form is already available locally.
Clinical Trial Evidence
Currently no related clinical trials registered for conjunctivitis.
Literature Evidence
Selected publications (no RCTs were identified; reviews and comparative studies are prioritised):
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 32959365 | 2020 | Review (Cochrane) | Cochrane Database Syst Rev | Interventions for preventing ophthalmia neonatorum (neonatal conjunctivitis) |
| 11270936 | 2001 | Review | Drugs | Comparative review of 16 topical ophthalmic antibacterial preparations |
| 38511104 | 2024 | Comparative study | Curr Ther Res | Moxifloxacin compared with chloramphenicol for bacterial eye infections |
| 8800624 | 1996 | Review | Drug Safety | Debate over a possible link between ocular chloramphenicol and aplastic anaemia |
| 7498557 | 1995 | Review | Eye | Appropriate use and misuse of topical chloramphenicol |
| 25833086 | 2015 | Review | Clin Exp Ophthalmol | Concerns about over-the-counter chloramphenicol |
| 3300139 | 1987 | Randomized comparison (open) | Acta Ophthalmol | In Tanzania, fusidic acid had a higher clinical success rate (93%) than chloramphenicol (48%) and framycetin (74%) in acute conjunctivitis |
| 3554881 | 1987 | Randomized comparison (single-blind) | Acta Ophthalmol | Clinical success of 81% with chloramphenicol vs 84% with fusidic acid in purulent conjunctivitis; more trivial local side effects with chloramphenicol |
| 7153511 | 1982 | Clinical/laboratory study | J Hyg | Chloramphenicol drops delayed and reduced signs of chlamydial neonatal conjunctivitis, but 85% of treated infants remained culture-positive |
| 22186318 | 2012 | Experimental | Pak J Pharm Sci | Chloramphenicol niosomes compared with 0.5% eye drops in experimental conjunctivitis in rabbits |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN00230P | Chloramphenicol Ear Drops 5% w/v | Solution | Not stated in the licence record |
| SIN04574P | Chloramphenicol Ear Drops 5% w/v | Solution | Not stated in the licence record |
| SIN00231P | Xepanicol Eye Drops 0.5% | Solution | Not stated in the licence record |
Cytotoxicity
Chloramphenicol is an antibacterial, not an antineoplastic drug, so this section does not apply.
Safety Considerations
- Contraindications / conditions of concern (from the drug-disease knowledge graph, not from label text): kidney disease, liver disease, gallbladder disease, peripheral neuropathy, optic neuritis, acute intermittent porphyria, and a range of blood disorders, namely anaemia, aplastic anaemia, thrombocytopenia, agranulocytosis, neutropenia (including congenital forms), and paroxysmal nocturnal haemoglobinuria.
- Literature-based concerns: the possible link between ocular chloramphenicol and aplastic anaemia remains debated, and over-the-counter misuse has been raised as a concern.
- Drug Interactions (100 interactions recorded; examples):
- Major: cisapride, naloxegol
- Moderate: sulfonylurea antidiabetics (glimepiride, glipizide, glyburide, chlorpropamide, acetohexamide), repaglinide, saxagliptin, simvastatin, rosuvastatin, metronidazole, aprepitant, budesonide, iron, eliglustat, nitisinone, balsalazide, naldemedine
Package insert warnings were not available for this review; please refer to the package insert for full safety information.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Topical chloramphenicol for bacterial conjunctivitis is established practice, and the Singapore market already has an eye drop product. The evidence is limited to reviews and older comparative studies (L3), with no registered trials, and efficacy in some studies was equal or inferior to alternatives. Haematological safety concerns call for guardrails.
To proceed, the following is needed:
- Singapore package insert warnings and contraindications for the eye drop product, plus the approved indication text, which is missing from the licence records
- Mechanism of action data from DrugBank
- Confirmation of the approved ocular indication for SIN00231P
- Guardrails for use: topical-only use, short courses, and a screening for history of blood disorders or bone marrow suppression
- Review of current local resistance patterns and comparison with alternative topical antibiotics
Other predicted indications (not recommended at this time, Hold): diffuse scleroderma, postinfectious vasculitis, post-bacterial disorder, post-infectious syndrome, infective urethral stricture, Chagas cardiomyopathy, infection-related haemolytic uraemic syndrome, punctate epithelial keratoconjunctivitis and chronic rhinosinusitis. These are supported only by model prediction or by literature that does not evaluate chloramphenicol as a treatment (for example, the scleroderma papers use chloramphenicol only as a laboratory reporter assay tool).
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.