Doxycycline
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Doxycycline: From Bacterial Infections to Punctate Epithelial Keratoconjunctivitis
One-Sentence Summary
Doxycycline is a tetracycline-class antibiotic. The SAHPRA registration data supplied contain no approved-indication text, so this describes its general use against bacterial infections. The TxGNN model predicts it may be effective for punctate epithelial keratoconjunctivitis. Evidence is very thin: 0 clinical trials and 1 publication, a 1992 case report that does not test doxycycline as a treatment for this condition.
Quick Overview
| Item | Content |
|---|---|
| Predicted New Indication | Punctate epithelial keratoconjunctivitis |
| TxGNN Prediction Score | 99.94% |
| Evidence Level | L4 |
| South Africa Market Status | Marketed |
| Number of SAHPRA Registrations | 4 (3 unique registration numbers) |
| Recommended Decision | Hold |
The original indication is not shown in the table because the SAHPRA records supplied contain no approved-indication text.
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available. Doxycycline is a broad-spectrum antibiotic. It is an established treatment for chlamydial conjunctivitis, so it may be mechanistically applicable to eye-surface disease with an infectious trigger.
The only supporting paper describes two patients who developed punctate epithelial keratitis after chlamydial follicular conjunctivitis. Both had been treated with oral tetracycline or doxycycline, and the follicles resolved. The punctate corneal lesions then appeared after treatment, and recurred. The link is therefore indirect. It shows that doxycycline treats the preceding infection, not that it treats punctate epithelial keratoconjunctivitis itself.
Doxycycline may also have anti-inflammatory effects on the ocular surface through inhibition of matrix metalloproteinases (MMPs). This is speculative and not supported by the data provided.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 1424659 | 1992 | Case report/series | Cornea | Two cases of chlamydial follicular conjunctivitis, treated with oral tetracycline or doxycycline, were followed by recurrent bilateral punctate epithelial keratitis. The follicles resolved, but the corneal lesions persisted or recurred. |
South Africa Market Information
| Registration Number | Product Name | Dosage Form |
|---|---|---|
| Reg. No. 31/20.1.1/0425 | Doxycycline biotech | Tablet |
| Reg. No. 32/20.1.1/0254 | Doxytet | Capsule |
| Reg. No. 32/20.1.1/0117 | Doxymed | Tablet (listed twice in the source data) |
All products are oral. Approved-indication text and Essential Medicines List (EML) status were not available in the data supplied.
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
Conclusion and Next Steps
Decision: Hold
Rationale: The high TxGNN score is backed by a single 1992 case report. That report shows doxycycline treating the preceding chlamydial infection, not the punctate keratitis that followed, and no clinical trials are registered. The evidence does not yet justify moving forward.
To proceed, the following is needed:
- SAHPRA package insert warnings and contraindications (a blocking gap for safety screening)
- Mechanism of action data, for example from the DrugBank API
- Controlled clinical evidence in punctate epithelial keratoconjunctivitis, including any trials in the SANCTR or PACTR registers
- A route-compatibility assessment. Only oral tablet and capsule forms are registered, so an ophthalmic formulation would be a separate question.
- Consider prioritising other predictions in the same Evidence Pack that have more supporting literature, such as chronic gingivitis and periodontitis, where the literature covers locally delivered and sub-antimicrobial-dose doxycycline
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.