An Early Phase 1 interventional study of Suzetrigine and Lidocaine (drug) in Pain, Acute Pain and Healthy Volunteer Study, sponsored by Medical University of Vienna. Completed at 1 site in Austria. Open to participants aged 18 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-24.
Sponsored by Medical University of Vienna · Early Phase 1, Interventional, and Basic science
This study aims to understand how NaV1.8, a specific type of sodium channel found in peripheral nerves, contributes to different types of pain in humans. To address this, suzetrigine, a highly selective blocker of the NaV1.8 channel, is used. While current pain medications often have side effects that limit their use, NaV1.8 is a promising target for new, non-opioid pain treatments because it is primarily located in the nerves that send pain signals to the brain.
This study is a randomised, placebo-controlled double-blind crossover microdosing trial. This means that very small, safe amounts of the drug are injected directly into the skin of healthy volunteers to observe its effects locally. This approach ensures the drug works only at the injection site with negligible exposure to the rest of the body.
Healthy volunteers will undergo six different types of brief, controlled pain tests to see which ones are reduced by blocking NaV1.8.
These tests are as follows:
By comparing the effects of suzetrigine against a placebo and a standard local anaesthetic (lidocaine), the study will help determine which specific pain modalities critically depend on NaV1.8.
Study Objective:
The primary objective of this trial is to evaluate the analgesic efficacy of selective NaV1.8 inhibition across multiple established experimental human pain models. While selective NaV1.8 inhibitors like suzetrigine have demonstrated success in clinical trials for acute post-surgical pain, it remains unknown whether their efficacy is modality-specific in humans. This study seeks to bridge that gap by testing mechanical, electrical, chemical, and thermal pain induction.
Study Design:
This is a randomised, placebo-controlled double-blind crossover microdosing trial involving healthy volunteers. To isolate the role of NaV1.8 without systemic side effects, the study utilises an intracutaneous microdosing approach. Suzetrigine (1 µM) is administered via local injection, providing an effective local concentration while resulting in a total dose (\~1.53 µg) that is approximately 32,000-fold lower than therapeutic oral doses.
Methodology and Pain Modalities:
Participants will receive injections of suzetrigine, a positive control (lidocaine 2 mM), or a negative (vehicle) control at separate, randomised sites on the volar forearms. Subjective pain will be rated on a numerical scale of 0 to 100.
The following six modalities will be tested:
Hypotheses:
The primary hypotheses are that selective NaV1.8 inhibition will significantly reduce pain scores (or the area under the curve for prolonged stimuli) compared to the vehicle control for each of the six modalities. The secondary hypothesis is that the degree of pain reduction will differ significantly across the various modalities, indicating a modality-specific profile for NaV1.8 in human sensory processing.
Safety and Rationale:
Suzetrigine (marketed as Journavx in the US) has been extensively tested in phase II and III trials and was found to be well-tolerated with no significant CNS or cardiovascular adverse effects. The microdosing model used here further minimises risk by ensuring negligible systemic exposure. Findings from this study will provide critical guidance for the development of future sodium channel inhibitors and the selection of clinical models for testing.
1,073 studies on the registry are indexed under Acute Pain; 166 are open to participants now.
This study's enrollment of 67 is below the median of 86 across 902 interventional studies indexed under Acute Pain.
Browse Acute Pain studies →Medical University of Vienna is the lead sponsor of 1,109 studies on the registry; 184 are open to participants now.
Compared within Acute Pain, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Pain. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Inclusion criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants receive intracutaneous injections of suzetrigine at a concentration of 1 µM before or during experimental pain induction across six different modalities (electrical, mechanical, capsaicin, acid, heat, and cold).
Drug: Suzetrigine
Participants receive intracutaneous injections of lidocaine (positive control) at a concentration of 2 mM before or during experimental pain induction across three out of six different modalities (electrical, mechanical, capsaicin).
Drug: Lidocaine (drug)
Participants receive intracutaneous injections of control solution (negative control) before or during experimental pain induction across six different modalities (electrical, mechanical, capsaicin, heat, and cold).
Drug: Control Solution
A selective NaV1.8 inhibitor. It is administered at a concentration of 1 µM via intracutaneous injection at the site of pain induction. The total dose per subject is 1.53 µg.
A non-selective NaV inhibitor. It is administered at a concentration of 2 mM via intracutaneous injection at the site of pain induction. The total dose per subject is 120 µg.
A control solution mimicking extracellular fluid. It is administered via intracutaneous injection at the site of pain induction.
Pain Intensity: Electrical stimulation
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The average of all provided pain ratings divided by the number of delivered stimuli (maximum of 23 stimuli). If a subject stops the test upon reaching a rating of 30, the average is calculated based on the actual number of stimuli delivered.
Time frame: 1.5 minutes post-injection.
Geometric Mean Pain Intensity: Mechanical stimulation
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The geometric mean of the pain ratings recorded from three standardized mechanical stimuli (3.6N force).
Time frame: 1.5 minutes post-injection.
Area Under the Curve (AUC): Capsaicin injection
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The AUC of pain ratings provided every 5 seconds, starting from the time of injection until a consecutive rating of 0 is maintained for 30 seconds.
Time frame: From injection until 0 pain for 30 seconds.
Area Under the Curve (AUC): Acid injection
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The AUC of pain ratings provided every 5 seconds during the pH decrease from 7.2 to 5.4.
Time frame: 110 seconds
Area Under the Curve (AUC): Heat injection
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The AUC of pain ratings provided every 5 seconds during the temperature increase from 23°C to 52°C.
Time frame: 150 seconds
Area Under the Curve (AUC): Cold injection
Metric: Numerical Rating Scale (0-100; 0=No pain, 100=Worst imaginable pain). Calculation: The AUC of pain ratings provided every 5 seconds during the temperature decrease from 23°C to 4°C.
Time frame: 150 seconds
Plan to share: Yes — De-identified individual participant data (IPD), including pain ratings, time- stamped injection responses, and basic demographics (age, sex), will be shared alongside the publication of the primary results. Only data used in the main publication and relevant supplementary analyses will be included.
Supporting information: Study protocol, Statistical analysis plan, Analytic code
Time frame: IPD will be made available at the time of publication of the primary results article, as a supplementary file.
Access criteria: All individuals who have access to the published article will be able to access the individual participant data (IPD) and supporting information as supplementary material. No special request or data use agreement is required.
No publications or documents are linked to this record.
Ran from Apr 2026 to primary completion in Jun 2026, 1 month.
Of 33 phase 1 interventional studies under Acute Pain, half reached primary completion within 7 months of starting (the median), counting those still running; a quarter within 3 and three quarters within 17. This study's 1 month is below that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Suzetrigine
Medical University of Vienna →