Prilocaine

證據等級: L5

預測適應症: 10 個

Prilocaine: From Local Anesthesia to Neuralgia

One-Sentence Summary

Prilocaine is an amide-type local anesthetic, most widely used in combination with lidocaine as the eutectic mixture EMLA® cream for topical/regional anesthesia. Among 10 TxGNN-predicted indications, Neuralgia (particularly postherpetic neuralgia) stands out as the only candidate with substantive supporting evidence, with 12 clinical trials and 20 publications identified, including several completed RCTs on lidocaine-prilocaine cream in postherpetic neuralgia.

Note: TxGNN generated 10 candidate indications for prilocaine in this evidence pack; the other 9 (e.g., papillary conjunctivitis, manic bipolar disorder, bronchitis, allergic asthma, rosacea conjunctivitis) had no clinical trial or literature support and were scored L4–L5/Hold. This report focuses on the one candidate (Neuralgia) that reached decision stage S3.

Quick Overview

Item	Content
Original Indication	Not formally registered in this dataset — clinically established as a local/regional anesthetic (typically combined with lidocaine as EMLA cream)
Predicted New Indication	Neuralgia (postherpetic neuralgia)
TxGNN Prediction Score	99.34%
Evidence Level	L2
Norway Market Status	✗ Not marketed
Number of Authorizations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in this evidence pack (DG002). Based on established pharmacology, prilocaine is an amide-type local anesthetic that, after topical or subcutaneous administration, blocks voltage-gated sodium channels on peripheral neurons, inhibiting depolarization and action potential propagation. It is most commonly used clinically as part of EMLA (eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) for procedural and dermatologic anesthesia.

Neuralgia — especially postherpetic neuralgia (PHN) — is characterized by aberrant peripheral sensory nerve firing and sensitization. Sodium-channel blockade by prilocaine (in combination with lidocaine) provides a mechanistically plausible route to reducing this abnormal signaling, and EMLA cream already has decades of clinical use for neuralgic pain relief, both as a standalone analgesic and as a pretreatment to reduce procedural pain (e.g., before capsaicin 8% patch application).

The key limitation is that essentially all supporting evidence involves prilocaine in combination with lidocaine (EMLA), not prilocaine as monotherapy. No identified trial isolates prilocaine's independent contribution to neuralgia relief.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT00916942	Phase 2	Completed	20	Open-label study of topical lidocaine 2.5%/prilocaine 2.5% cream as pre-treatment for NGX-4010 (capsaicin patch) in postherpetic neuralgia
NCT06247592	N/A	Unknown	70	Greater occipital nerve block using 2% prilocaine vs pulsed radiofrequency in chronic migraine
NCT06899438	N/A	Completed	38	Prilocaine injection vs botulinum toxin A compared for myofascial pain syndrome trigger points
NCT07021365	N/A	Not yet recruiting	30	Ganglion impar radiofrequency ablation vs phenol neurolysis for chronic coccydynia (local-anesthetic-based nerve block techniques)
NCT03587220	N/A	Completed	44	Mechanistic study of capsaicin-induced desensitization combined with topical local anesthetic on cutaneous nociceptive C-fibers
NCT03220113	Phase 1/2	Unknown	100	De-Novo algorithm (dexamethasone, lidocaine, thiamine) injected into trigeminal/occipital nerve branches for chronic craniofacial neuralgia/migraine
NCT05411900	Phase 2	Unknown	164	RCT of repeated botulinum toxin A injections for peripheral neuropathic pain in carpal tunnel syndrome
NCT02736890	Phase 2	Terminated	8	Subcutaneous botulinum toxin A for at-level back pain in spinal cord injury
NCT01911377	Phase 2	Terminated	12	Botulinum toxin A for allodynic-type neuropathic pain in spinal cord injury/multiple sclerosis
NCT04914637	N/A	Completed	66	Dry needling combined with interlaminar epidural steroid injection for chronic neck pain from cervical disc herniation

Literature Evidence

PMID	Year	Type	Journal	Key Findings
2493878	1989	RCT	BMJ	Lignocaine-prilocaine cream significantly reduced pain in postherpetic neuralgia
2616182	1989	RCT	Pain	EMLA cream (5–10g, 24h application) significantly improved pain intensity in refractory PHN, including facial PHN subgroup
22182397	2011	RCT	BMC Anesthesiol	Lidocaine 2.5%/prilocaine 2.5% cream pretreatment improved tolerability of capsaicin 8% patch (NGX-4010) in PHN patients
1430539	1992	Review	J Dermatol Surg Oncol	EMLA reviewed as an effective, safe topical anesthetic, including use in postherpetic neuralgia
10353509	1999	Cohort	Pain	Single and repeated EMLA applications reduced spontaneous and evoked pain in PHN patients (n=11)
12378018	2002	Cohort	J Korean Med Sci	Identified prognostic factors (age, affected area, pain duration) for progression to postherpetic neuralgia
24310458	2013	Review	Turk Neurosurg	Evaluated invasive procedures for medically intractable genitofemoral/ilioinguinal neuralgia
23314014	2013	Review	Curr Opin Support Palliat Care	Evidence-based approach to managing persistent wound-related pain, including topical anesthetics
2046584	1991	Case report	Med J Aust	Early clinical report on EMLA cream use in herpetic neuralgia
1875823	1991	Case report	Med J Aust	Companion report on EMLA cream in herpetic neuralgia

Norway Market Information

Prilocaine currently has no marketing authorization on file in Norway (market status: 未上市 / Not marketed; total licenses: 0). No product-level dosage form or approved-indication data is available.

Safety Considerations

Please refer to the package insert for safety information. Formal key warnings, contraindications, and drug-drug interaction data (DG001) are not yet available for this drug in the current dataset and must be obtained from the TFDA/Norway product label before clinical use is expanded to a new indication.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: Three completed RCTs (tier 1) and one completed Phase 2 trial support lidocaine-prilocaine cream (EMLA) for pain relief in postherpetic neuralgia, with a coherent sodium-channel-blockade mechanism. However, prilocaine has not been tested as monotherapy, and it currently has no Norway market authorization.

To proceed, the following is needed:

Official TFDA/Norway package insert data — key warnings and contraindications (DG001, currently blocking)
Verified mechanism-of-action documentation from DrugBank or equivalent source (DG002)
Evidence isolating prilocaine's independent contribution versus the lidocaine-prilocaine combination
Assessment of methemoglobinemia and systemic absorption risk — a known class effect of prilocaine, particularly relevant if topical use is expanded to patients with compromised skin barrier
A regulatory pathway assessment, since prilocaine is not currently marketed in Norway (0 authorizations on file)
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.