Prilocaine
| 證據等級: L5 | 預測適應症: 10 個 |
目錄
Prilocaine: From Local Anesthesia to Postherpetic Neuralgia
One-Sentence Summary
Prilocaine is an amide-type local anesthetic, typically formulated with lidocaine as the eutectic mixture EMLA cream for topical/regional anesthesia. Among 10 candidate indications generated by TxGNN, only Neuralgia (specifically postherpetic neuralgia, PHN) is backed by real clinical and literature evidence — 1 completed Phase 2 trial and 10+ relevant publications dating back to 1989 support topical lidocaine/prilocaine use in this setting. The other 9 candidates (including the top-ranked "papillary conjunctivitis") have no supporting trials or literature and are held pending further evidence.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not available from regulatory data (drug not marketed in Germany/Taiwan); classified as an amide-type local anesthetic based on repurposing rationale |
| Predicted New Indication | Neuralgia (postherpetic neuralgia) |
| TxGNN Prediction Score | 99.34% |
| Evidence Level | L2 |
| Germany Market Status | ✗ Not Marketed |
| Number of Authorizations | 0 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed DrugBank mechanism-of-action data is currently unavailable (data gap DG002). Based on the mechanistic rationale documented for this candidate, prilocaine is an amide-type local anesthetic that, after topical or subcutaneous administration, blocks voltage-gated sodium channels on peripheral sensory neurons, suppressing abnormal nociceptor firing and pain signal transmission.
Prilocaine's most established clinical use is as a component of EMLA cream (2.5% lidocaine + 2.5% prilocaine), a eutectic mixture applied topically for procedural and neuropathic pain. Neuropathic pain conditions such as postherpetic neuralgia (PHN) share the same underlying pathophysiology — sensitized, hyperexcitable peripheral nerve fibers — that prilocaine's sodium-channel blockade is designed to target. This mechanistic overlap is supported by a long-standing body of clinical literature (1989–2026) on EMLA use in PHN, making it the most credible repurposing candidate among the 10 TxGNN predictions.
The other 9 predicted indications (papillary conjunctivitis, manic bipolar affective disorder, bronchitis, migraine disorder, migraine with brainstem aura, atopic eczema, allergic asthma, rhinitis, rosacea conjunctivitis) either have no supporting evidence, involve mismatched/unrelated trials, or only report prilocaine-related adverse reactions (e.g., contact allergy, systemic toxicity in atopic dermatitis) rather than therapeutic benefit. These remain appropriately scored as Hold.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00916942 | Phase 2 | Completed | 20 | Open-label study of 2.5% lidocaine/2.5% prilocaine cream as pre-treatment for NGX-4010 capsaicin patch in postherpetic neuralgia (PHN); directly tests the prilocaine combination in this indication |
| NCT06247592 | N/A | Unknown | 70 | Greater occipital nerve block (5cc 2% prilocaine) vs pulse radiofrequency in chronic migraine — confirms prilocaine's clinical use in peripheral nerve blockade for neuralgic pain |
| NCT01540877 | N/A | Completed | 28 | Human experimental model combining capsaicin sensitization with local anesthetic (LA) C-fiber block to study neuropathic pain mechanisms |
| NCT03587220 | N/A | Completed | 44 | Studied TRPV1+ fiber role in cutaneous inflammation; evaluated whether topical lidocaine desensitization interacts with capsaicin-induced nociceptive changes |
| NCT02736890 | Phase 2 | Terminated | 8 | Botulinum toxin A for spinal-cord-injury-related back pain; local anesthetic used as comparator/adjunct in pain trial context |
| NCT03220113 | Phase 1/2 | Unknown | 100 | De-Novo therapy (dexamethasone/lidocaine/thiamine) injected into trigeminal and occipital nerve branches for craniofacial neuralgia/chronic migraine |
| NCT01911377 | Phase 2 | Terminated | 12 | Botulinum toxin A for allodynic neuropathic pain in spinal cord injury/MS; local anesthetic-adjacent neuralgia trial context |
| NCT02537951 | N/A | Completed | 10 | Pilot study of autofluorescent flavoprotein imaging for diagnosing small fiber neuropathy, a common cause of neuralgic pain |
| NCT05411900 | Phase 2 | Unknown | 164 | RCT of botulinum toxin A for peripheral neuropathic pain in carpal tunnel syndrome |
| NCT07021365 | N/A | Not yet recruiting | 30 | Ganglion impar radiofrequency ablation vs phenol neurolysis for chronic coccydynia (neuralgic pain refractory to nerve block) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 2493878 | 1989 | Cohort | BMJ | Lignocaine-prilocaine cream (EMLA) evaluated as treatment for postherpetic neuralgia |
| 2616182 | 1989 | Cohort | Pain | 5% EMLA cream applied 24h significantly improved pain intensity scores (P<0.05) in 12 PHN patients, including facial PHN subgroup |
| 22182397 | 2011 | Cohort | BMC Anesthesiology | Lidocaine 2.5%/prilocaine 2.5% cream pretreatment improved tolerability of capsaicin 8% patch (NGX-4010) in PHN patients |
| 10353509 | 1999 | Cohort | Pain | Single and repeated EMLA applications reduced spontaneous and evoked pain in 11 PHN patients over 6 days |
| 8695081 | 1996 | Case Report | J Clin Anesth | EMLA cream successfully treated PHN that was resistant to other treatment modalities |
| 1430539 | 1992 | Review | J Dermatol Surg Oncol | EMLA (2.5% lidocaine/2.5% prilocaine) reviewed as effective, safe topical anesthetic, with noted use in postherpetic neuralgia |
| 12378018 | 2002 | Review | J Korean Med Sci | Identified prognostic factors (age ≥50, area ≥9%, pain duration ≥4wks) for progression to PHN, relevant to treatment timing |
| 41777672 | 2026 | Retrospective Cohort | Front Aging Neurosci | Compared EMLA alone vs paravertebral block + EMLA for improving tolerability of capsaicin 8% patch in thoracic PHN |
| 2046584 | 1991 | Case Series/Letter | Med J Aust | Early clinical report on EMLA cream use in herpetic neuralgia |
| 1875823 | 1991 | Case Series/Letter | Med J Aust | Correspondence discussing EMLA cream and herpetic neuralgia |
Safety Considerations
Please refer to the package insert for safety information. TFDA/BfArM labeling data (warnings, contraindications, drug interactions) is currently a blocking data gap and must be obtained before formal safety review can proceed.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Among 10 TxGNN-predicted indications for prilocaine, neuralgia (postherpetic neuralgia) is the only candidate supported by a completed clinical trial and a substantial, decades-long body of literature on topical lidocaine/prilocaine (EMLA) use in this exact condition. However, no RCT-level evidence isolates prilocaine's independent contribution (studies use the lidocaine-prilocaine combination), and safety labeling data is missing.
To proceed, the following is needed:
- Obtain TFDA/BfArM package insert (warnings, contraindications, DDI) — currently blocking (DG001)
- Confirm formal DrugBank MOA and original approved indication (DG002)
- Clarify prilocaine's independent efficacy contribution vs. the lidocaine-prilocaine (EMLA) combination
- Confirm route/formulation availability (topical cream) since the product is not currently marketed in Germany
- Keep the remaining 9 predicted indications on Hold pending new trial or literature evidence
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.