Permethrin
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Permethrin: From Scabies and Head Lice to Trombiculiasis
One-Sentence Summary
Permethrin is a pyrethroid ectoparasiticide, originally used to treat scabies and head lice. The TxGNN model predicts it may be effective for Trombiculiasis (chigger mite dermatitis), with no clinical trials and 1 publication (a veterinary case study) currently supporting this direction.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Scabies and head lice (based on known pharmacological use; no UK licensing text available in the evidence pack) |
| Predicted New Indication | Trombiculiasis |
| TxGNN Prediction Score | 95.16% |
| Evidence Level | L4 |
| UK Market Status | Not marketed |
| Number of Marketing Authorisations | 0 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism of action data from DrugBank is not currently available for this record. However, based on the pharmacological classification referenced in the evidence pack, Permethrin is a pyrethroid ectoparasiticide/acaricide that acts on the voltage-gated sodium channels of arthropod nerve cells, causing paralysis and death of the parasite. Its established human indications — scabies (caused by the mite Sarcoptes scabiei) and head lice (Pediculus humanus capitis) — both involve arthropod ectoparasite infestations of the skin.
Trombiculiasis is a pruritic dermatitis caused by the larval stage of chigger mites (family Trombiculidae, e.g. Neotrombicula autumnalis) feeding on the skin. Chigger mites and scabies mites both belong to the subclass Acari and share similar arthropod neurophysiology, making them susceptible to the same sodium-channel-targeting mechanism.
Because Permethrin’s mode of action targets a broad class of arthropod ectoparasites rather than a single species, extrapolation from scabies/lice to chigger mite dermatitis has reasonable biological plausibility (a “class effect” argument). This is supported by one veterinary case study showing efficacy against Neotrombicula autumnalis dermatitis in dogs, although direct human clinical data are currently lacking.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 14984153 | 2004 | Veterinary Clinical Study | The Journal of Small Animal Practice | Topical permethrin-pyriproxyfen combination resolved Neotrombicula autumnalis-induced moderate-to-severe pruritic dermatitis in 14 of 15 dogs within 1–3 weeks of treatment |
Note: This is a veterinary (canine) study only; no human data are currently available.
UK Market Information
Permethrin is currently not marketed in the UK according to this evidence pack, and no marketing authorisation records are available for reference.
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: Only a single preclinical/veterinary case study (L4) supports this prediction, with no human clinical trials, no UK marketing authorisation, and unresolved safety and mechanism-of-action data gaps. Despite a mechanistically plausible “class effect” rationale, current evidence is insufficient to justify progression.
To proceed, the following is needed:
- MHRA/SmPC warnings and contraindications data for Permethrin (currently a blocking data gap)
- Confirmed mechanism of action documentation from DrugBank
- Human clinical or case-series evidence specifically evaluating Permethrin for chigger mite dermatitis (trombiculiasis)
- Verification of UK marketing authorisation and licensed dosage forms
- Drug–drug interaction (DDI) data
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.