Hydroxychloroquine
| Evidence Level: L3 | Predicted Indications: 10 |
Table of Contents
- Hydroxychloroquine
- Hydroxychloroquine: From Rheumatoid Arthritis and Lupus to Folliculitis Decalvans
Hydroxychloroquine: From Rheumatoid Arthritis and Lupus to Folliculitis Decalvans
One-Sentence Summary
Hydroxychloroquine is an established antimalarial and immunomodulator, originally used for malaria, rheumatoid arthritis and lupus erythematosus. The TxGNN model predicts it may be effective for Quinquaud's folliculitis decalvans (a scarring hair-loss disease), but there are no registered clinical trials and only 5 publications, mainly a retrospective study and an expert position statement.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Rheumatoid arthritis, systemic lupus erythematosus, malaria, discoid lupus erythematosus (the Singapore licence records contain no approved-indication text, so these come from the knowledge graph) |
| Predicted New Indication | Quinquaud's folliculitis decalvans |
| TxGNN Prediction Score | 98.66% |
| Evidence Level | L3 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 5 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available in the data compiled for this report. Based on known information, hydroxychloroquine is an antimalarial with immunomodulatory effects. Its efficacy in rheumatoid arthritis and lupus is established, and mechanistically it may be applicable to inflammatory skin and hair disorders.
Folliculitis decalvans is a chronic, relapsing neutrophilic scarring alopecia with a dysregulated inflammatory component. Hydroxychloroquine is thought to inhibit Toll-like receptor signalling, reduce antigen presentation and lower pro-inflammatory cytokine production. These effects plausibly support its use as an adjuvant. A 5-year retrospective study of 49 patients suggests possible benefit, and the EADV task force statement addresses management of the condition. The evidence is limited to retrospective data and expert guidance, with no prospective trials.
Other predicted indications in the model output were also reviewed. Among them, alopecia areata has the most clinical data (one small Phase 4 open-label study and several case series, with conflicting results). Follicular mucinosis has several supportive case reports. The remaining predictions (telogen effluvium, rare genetic syndromes, rheumatoid nodulosis and others) have little or no supporting evidence.
Clinical Trial Evidence
Currently no related clinical trials registered for folliculitis decalvans.
For reference, trials registered under the lower-ranked prediction of alopecia areata include:
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00176982 | Phase 4 | Completed | 16 | Open-label study of hydroxychloroquine in alopecia areata/totalis. Small, uncontrolled and single-arm |
| NCT06512766 | N/A | Completed | 315 | Retrospective study of systemic treatments (including HCQ) in lichen planopilaris and frontal fibrosing alopecia |
| NCT06512753 | N/A | Unknown | 56 | HCQ vs methotrexate in lichen planopilaris (patient preference trial) |
| NCT07190534 | N/A | Not yet recruiting | 50 | HCQ vs methotrexate in frontal fibrosing alopecia (patient preference trial) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 39340420 | 2025 | Retrospective cohort | Clin Exp Dermatol | 5-year study of 49 patients. HCQ may be beneficial as an adjuvant therapy for folliculitis decalvans |
| 40230058 | 2025 | Review (expert position statement) | J Eur Acad Dermatol Venereol | EADV task force statement on managing folliculitis decalvans. Therapy aims to control inflammation and prevent further hair loss |
| 39893632 | 2025 | Review | Expert Opin Drug Metab Toxicol | Comprehensive review of efficacy, safety and tolerability of drugs for alopecia |
| 41915583 | 2026 | Retrospective cohort | Acta Dermatovenerol Alp Pannonica Adriat | 15-year study of 109 patients with primary cicatricial alopecia: clinical features, treatments and course |
| 32030059 | 2019 | Case report | Int J Trichology | Treatment-resistant folliculitis decalvans controlled with adalimumab (not HCQ). Lists HCQ among the options |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN12213P | PLAQUENIL TABLET 200 mg (White) | Tablet, film coated | Not specified in the data |
| SIN16632P | HCQS HYDROXYCHLOROQUINE TABLET BP 200 mg | Tablet, film coated | Not specified in the data |
| SIN16475P | ACCOQUIN FILM COATED TABLET 200 MG | Tablet, film coated | Not specified in the data |
| SIN11874P | HALOXIN TABLET 100 mg | Tablet, sugar coated | Not specified in the data |
| SIN12669P | HALOXIN TABLET 200 mg | Tablet, sugar coated | Not specified in the data |
All five licences are valid single-ingredient oral tablets.
Safety Considerations
- Conditions flagged as contraindications or cautions in the knowledge graph (not taken from label text): porphyria and other porphyrin metabolism disorders, liver disease, gallbladder disease, eye disease including retinal disease, retinitis, scotoma, vision disorder and blindness, psoriasis and parapsoriasis, neutropenia, agranulocytosis, anaemia (including macrocytic anaemia), G6PD deficiency, substance abuse/dependence, glycogen storage disease, cystinuria and galactosemia.
- Drug Interactions: 100 interactions were recorded. Those listed in the data include:
- Major: clarithromycin, dolasetron, palonosetron
- Moderate: famotidine, cimetidine, loperamide, aprepitant, bisacodyl, metronidazole, and antidiabetic agents (chlorpropamide, glimepiride, and several insulins), among others
Please refer to the package insert for the full warnings and contraindications.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction score is very high, but the evidence for folliculitis decalvans is limited to one retrospective cohort and an expert statement, with no registered trials. In addition, the safety data (package insert warnings and contraindications) are incomplete, which prevents safety screening. The case is better treated as a research question than as a candidate for immediate action.
To proceed, the following is needed:
- Package insert warnings and contraindications from HSA (a blocking gap for safety screening)
- Mechanism of action data (for example from DrugBank)
- Prospective or controlled data for HCQ in folliculitis decalvans
- Eye safety (retinal toxicity) monitoring plan, given the eye-disease flags and long-term use in a chronic condition
- Review of alopecia areata and follicular mucinosis as alternative lead indications, given their larger bodies of clinical evidence
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.