Sulfamethoxazole
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
- Sulfamethoxazole
- Sulfamethoxazole: From Systemic Antibacterial Use to Acute Contagious Conjunctivitis
Sulfamethoxazole: From Systemic Antibacterial Use to Acute Contagious Conjunctivitis
One-Sentence Summary
Sulfamethoxazole is a sulfonamide antibacterial, sold in South Africa mainly as co-trimoxazole products. The TxGNN model predicts it may be effective for acute contagious conjunctivitis. Support is thin: 0 clinical trials and 1 publication, an indirect antibiotic-susceptibility study.
Quick Overview
| Item | Content |
|---|---|
| Predicted New Indication | Acute contagious conjunctivitis |
| TxGNN Prediction Score | 99.63% |
| Evidence Level | L4 |
| South Africa Market Status | Marketed |
| Number of SAHPRA Registrations | 7 |
| Recommended Decision | Hold |
The registration records provided contain no approved-indication text, so the original indication cannot be quoted from the SAHPRA data.
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the Evidence Pack. Based on general pharmacology, sulfamethoxazole is a sulfonamide antibacterial that inhibits bacterial dihydropteroate synthase, which blocks folate synthesis in susceptible bacteria.
Acute contagious conjunctivitis is commonly bacterial and is usually treated empirically with antibiotics. An antibacterial mechanism is therefore biologically plausible. This is a plausibility argument only.
The very high TxGNN score is a model output, not clinical proof. The only supporting paper is a susceptibility study, which does not show that sulfamethoxazole works for this condition. The other nine predicted indications are also on Hold. Most rest on the model prediction alone (L5), and several have no plausible antibacterial link (for example endocardial fibroelastosis and post-infectious syndromes).
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 31788487 | 2019 | Cohort (retrospective) | Med Hypothesis Discov Innov Ophthalmol J | Bacteriology and antibiotic susceptibility patterns in childhood acute bacterial conjunctivitis at a paediatric hospital in Western Greece. It describes the causative organisms and susceptibility, not the efficacy of sulfamethoxazole. |
South Africa Market Information
Five of the seven registrations were provided in the Evidence Pack:
| Registration Number | Product Name | Dosage Form |
|---|---|---|
| Z/20.2/209 | Trixazole | Tablet |
| K/20.2.1/335 | Spectrim | Capsule |
| L/20.2/336 | Purbac injection 5ml | Injection |
| 28/20.2/0389 | Xerazole Suspension | Suspension |
| W/20.2.1/88 | Co-Trimoxazole 960 Biotech | Tablet |
Available forms are oral (tablet, capsule), injectable, suspension and syrup. No ophthalmic (topical eye) formulation is registered, and route compatibility for an eye indication has not been assessed.
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
One literature signal is worth noting. A 1985 case report (PMID 3157322) describes erythema multiforme in a child after topical sulfacetamide, another sulfonamide, used for conjunctivitis. The child had earlier tolerated trimethoprim-sulfamethoxazole. It is a single case, but it is a reminder to consider sulfonamide hypersensitivity in any ocular repurposing work.
Conclusion and Next Steps
Decision: Hold
Rationale: There are no clinical trials and only one indirect susceptibility paper. Neither shows efficacy in conjunctivitis. The registered products are systemic, with no eye formulation, and safety data have not been reviewed.
To proceed, the following is needed:
- SAHPRA package insert warnings and contraindications (a blocking gap for safety screening)
- Detailed mechanism of action data (for example from DrugBank)
- Approved indication text for the registered products
- Direct clinical evidence, such as comparative trials of sulfonamide-based therapy in bacterial conjunctivitis
- A route and formulation assessment, since no ophthalmic product is registered and systemic use would need justification
- Local susceptibility data for the likely conjunctival pathogens
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.