Trimethoprim
| Evidence Level: L5 | Predicted Indications: 2 |
Table of Contents
Trimethoprim: From Bacterial Infections to Punctate Epithelial Keratoconjunctivitis
One-Sentence Summary
Trimethoprim is a dihydrofolate reductase (DHFR) inhibitor, traditionally used as an antibacterial agent for infections such as urinary tract infections. The TxGNN model predicts it may be effective for Punctate Epithelial Keratoconjunctivitis, but currently no clinical trials and no published literature directly support this specific prediction — the model’s top-ranked candidate for this drug is not yet backed by clinical evidence.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Bacterial infections (e.g. urinary tract infection) — specific regulatory indication text not available in this evidence pack |
| Predicted New Indication | Punctate Epithelial Keratoconjunctivitis |
| TxGNN Prediction Score | 99.57% |
| Evidence Level | L5 |
| 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 information, trimethoprim is a folate-pathway antibacterial that inhibits bacterial dihydrofolate reductase (DHFR), blocking synthesis of tetrahydrofolate and thereby bacterial DNA/protein synthesis. Its efficacy against common ocular surface pathogens (e.g. Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae) is well established in combination ophthalmic products such as trimethoprim–polymyxin B (Polytrim).
Punctate epithelial keratoconjunctivitis and bacterial conjunctivitis share overlapping infectious ocular-surface pathophysiology, which is the mechanistic basis for this prediction. However, the evidence pack’s own rationale notes that this specific prediction is a broad generalisation by the TxGNN model across the “ocular surface infection” disease category, rather than a finding drawn from direct clinical data — no trials or publications specific to punctate epithelial keratoconjunctivitis were identified.
Notably, a closely related candidate indication in the same evidence pack — conjunctivitis — is supported by a Phase 4 head-to-head RCT (trimethoprim–polymyxin B vs moxifloxacin) and multiple further publications, with an evidence level of L2 and a “Proceed with Guardrails” recommendation. This adjacent, better-evidenced indication lends indirect plausibility to the antibacterial mechanism being applicable to ocular surface infections generally, even though it does not constitute direct support for punctate epithelial keratoconjunctivitis specifically.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
Currently no related literature available.
Safety Considerations
Please refer to the SmPC and BNF for safety information. Report suspected adverse reactions via the Yellow Card Scheme.
Conclusion and Next Steps
Decision: Hold
Rationale: This prediction is currently supported by a TxGNN model score alone (Evidence Level L5), with no clinical trials or literature specific to punctate epithelial keratoconjunctivitis. The drug is also not currently marketed in the UK, and key safety/regulatory data (warnings, contraindications, MOA) are missing, which blocks initial safety screening.
To proceed, the following is needed:
- MHRA/SmPC label data — key warnings, contraindications and drug interactions
- Confirmed mechanism of action (MOA) documentation from DrugBank or equivalent source
- Targeted literature/trial search specific to punctate epithelial keratoconjunctivitis (rather than the broader conjunctivitis category)
- Consideration of whether the better-evidenced adjacent indication (bacterial conjunctivitis, L2, Proceed with Guardrails) should be prioritised ahead of this candidate
- UK market and licensing status confirmation, given the current evidence pack shows the drug as not marketed
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.