Prilocaine
| Evidence Level: L2 | Predicted Indications: 10 |
Table of Contents
Prilocaine: From Local Anesthesia to Neuralgia (Postherpetic Neuralgia)
One-Sentence Summary
Prilocaine is an amide-type local anesthetic best known as a component of EMLA cream (with lidocaine); it is not currently marketed in Taiwan. Among the 10 TxGNN-predicted indications for this drug, Neuralgia (particularly postherpetic neuralgia) is the only candidate with substantive evidence — 12 clinical trials and 20 publications — so this report focuses on it rather than the top-scored but evidence-free candidate (papillary conjunctivitis).
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Local anesthesia (amide-type); no formal TFDA-approved indication text available — drug not marketed in Taiwan |
| Predicted New Indication | Neuralgia (incl. postherpetic neuralgia) |
| TxGNN Prediction Score | 99.34% |
| Evidence Level | L2 |
| Taiwan Market Status | Not marketed (Not marketed) |
| Number of Registrations | 0 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed structured mechanism-of-action data is not available in DrugBank for this evidence pack (flagged as a High-severity data gap). However, the evidence pack’s own trial and literature annotations consistently describe prilocaine as an amide-class local anesthetic that blocks voltage-gated sodium channels, suppressing depolarization and abnormal firing of peripheral sensory nerve fibers.
Neuralgia — especially postherpetic neuralgia (PHN) — is a condition driven by exactly this kind of aberrant peripheral nerve signaling. Prilocaine already has an established clinical role here: combined with lidocaine as EMLA cream (eutectic mixture of local anesthetics), it has been directly studied for pain relief in PHN since the late 1980s. This is therefore not a novel mechanistic hypothesis but an extension of already-documented clinical use of the lidocaine/prilocaine combination into a more clearly defined neuralgia indication.
The main caveat is that most supporting evidence tests the lidocaine + prilocaine combination (EMLA) rather than prilocaine monotherapy, so attribution of effect to prilocaine alone remains uncertain.
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 (PHN) |
| NCT01540877 | NA | Completed | 28 | Human experimental neuropathic pain model combining capsaicin sensitization with local anesthetic (incl. prilocaine-type) C-fiber block |
| NCT06247592 | NA | Unknown | 70 | Greater occipital nerve block using 2% prilocaine vs. pulsed radiofrequency in chronic migraine |
| NCT03220113 | Phase 1/2 | Unknown | 100 | Trigeminal/occipital nerve block (dexamethasone, lidocaine, thiamine) for craniofacial neuralgia and chronic migraine |
| NCT03587220 | NA | Completed | 44 | TRPV1/capsaicin-induced desensitization mechanism study; evaluates prior topical lidocaine local anesthesia effect |
| NCT06899438 | NA | Completed | 38 | Prilocaine vs. Botulinum toxin A compared prospectively for myofascial pain syndrome |
| NCT05411900 | Phase 2 | Unknown | 164 | Botulinum toxin A for peripheral neuropathic pain in carpal tunnel syndrome (comparator study; no prilocaine arm) |
| NCT01911377 | Phase 2 | Terminated | 12 | Botulinum toxin A for allodynic neuropathic pain in spinal cord injury/MS (terminated) |
| NCT02736890 | Phase 2 | Terminated | 8 | Subcutaneous botulinum toxin A for at-level back pain in spinal cord injury (terminated) |
| NCT07021365 | NA | Not yet recruiting | 30 | Ganglion impar radiofrequency ablation vs. phenol neurolysis for chronic coccydynia (weak relevance — nerve-block technique, not prilocaine-specific) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 2493878 | 1989 | Clinical Study | BMJ | Lignocaine-prilocaine cream evaluated in postherpetic neuralgia |
| 2616182 | 1989 | Clinical Trial (efficacy & PK) | Pain | EMLA cream (5% or 10g) significantly improved pain intensity scores in PHN at 6 hours |
| 10353509 | 1999 | Clinical Study | Pain | Single and repeated EMLA applications reduced spontaneous and evoked pain in 11 PHN patients |
| 22182397 | 2011 | Clinical Trial (tolerability) | BMC Anesthesiology | Lidocaine 2.5%/prilocaine 2.5% cream pretreatment improved tolerability of NGX-4010 capsaicin patch in PHN |
| 41777672 | 2026 | Retrospective cohort | Frontiers in Aging Neuroscience | EMLA alone vs. paravertebral block + EMLA for tolerability of capsaicin patch in thoracic PHN |
| 10342425 | 1999 | Clinical Study | Pain | EMLA (2.5% prilocaine/2.5% lidocaine) pretreatment tested against topical capsaicin-induced pain |
| 1430539 | 1992 | Review | J Dermatol Surg Oncol | Review of EMLA (lidocaine-prilocaine) as effective topical anesthetic, including use in postherpetic neuralgia |
| 8695081 | 1996 | Case Report | J Clinical Anesthesia | Successful treatment of therapy-resistant PHN with EMLA cream |
| 2046584 | 1991 | Case Series | Medical J Australia | EMLA cream and herpetic neuralgia |
| 1875823 | 1991 | Case Series | Medical J Australia | EMLA cream and herpetic neuralgia (correspondence) |
Taiwan Market Information
Prilocaine currently has no marketing authorization in Taiwan (market status: Not marketed; total registrations: 0). No license records are available to summarize product name, dosage form, or approved indication text.
Safety Considerations
- Drug Interactions: 22 interactions recorded (source: DDInter). 18 are rated Major, dominated by two patterns: (1) methemoglobinemia-risk agents — Chloroquine, Primaquine, Quinine, Tafenoquine, Dapsone, Dapsone (topical), Nitrous acid, Nitric Oxide, Amyl Nitrite, Rasburicase; and (2) additive local anesthetic toxicity — Lidocaine, Lidocaine (topical), Benzocaine (topical), Cinchocaine (topical), Silver nitrate (topical), Silver sulfadiazine (topical). Also Major: Metoclopramide, Sulfasalazine. One Moderate interaction (Morphine, liposomal) and one Minor interaction (Hyaluronidase) were also recorded.
Formal TFDA warnings and contraindications are not yet available (flagged as a Blocking data gap) — please refer to the package insert once available before clinical use.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Neuralgia (particularly postherpetic neuralgia) is supported by decades of direct clinical evidence for the lidocaine/prilocaine (EMLA) combination, giving it L2 evidence strength — the only one of prilocaine’s 10 TxGNN-predicted indications to clear a research-actionable evidence bar. The remaining 9 candidates (e.g., papillary conjunctivitis, manic bipolar disorder, bronchitis, migraine, atopic eczema, allergic asthma, rhinitis) lack clinical or mechanistic support and are recommended Hold.
To proceed, the following is needed:
- TFDA package insert data (warnings, contraindications) — currently a blocking gap
- Formal DrugBank/structured MOA documentation for prilocaine monotherapy
- Evidence separating prilocaine monotherapy effects from the lidocaine/prilocaine (EMLA) combination product
- A Taiwan market-entry/licensing assessment, since the drug is not currently registered
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.