PainEarly Phase 1NCT07511400
The Role of NaV1.8 in Human Pain Models
A Early Phase 1 study testing Suzetrigine and Lidocaine (drug) in people with Pain and Acute Pain, run by Medical University of Vienna at 1 site in Austria.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Pain, Acute Pain, Healthy Volunteer Study
- What is being tested?
- Suzetrigine and Lidocaine (drug)
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 67 participants
- Where
- 1 siteAustria
- Study dates
- 21 Apr 2026to 9 Jun 2026
- Phase
- Early Phase 1
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Age between 18 and 70 years
- Full legal capacity Exclusion criteria
- Participant of another study, ongoing or within the last 4 weeks
- Medication intake (except contraception) or drug abuse
- Female subjects: Positive pregnancy test or breastfeeding
- Verified body temperature above 38°C
Show all 9Show fewer
- Known allergic diseases, in particular asthmatic disorders
- Limited accessibility of forearms (e.g. orthopedic cast)
- Sensory deficit, skin disease or hematoma at the forarms
Who cannot join
None listed.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Role of NaV1.8 in Human Pain Models - a Randomized, Placebo-controlled Crossover Microdosing Trial
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.
Read more
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:
- Electrical stimulation: Brief electrical pulses delivered onto the skin.
- Mechanical stimulation: A standardised "pin-prick" stimulation of the skin.
- Chemical stimulation: An injection of fluid containing capsaicin (the active component of chilli peppers) superficially into the skin.
- Heat stimulation: An injection of hot fluid superficially into the skin.
- Cold stimulation: An injection of cold fluid superficially into the skin.
- Acid stimulation: An injection of acidic fluid superficially into the skin.
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.
Read the detailed description
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:
- Electrical Stimulation: Epicutaneous delivery of 5-pulse trains (0.6 ms duration) at 1.5 minutes post-injection.
- Mechanical Stimulation: Suprathreshold pin-prick stimulation using a standardised device at 1.5 minutes post-injection.
- Chemical Stimulation: Intradermal injection of 7.6 ng capsaicin to trigger a transient burning pain sensation.
- Heat Stimulation: A defined, non-hazardous intradermal heat stimulus with increasing temperature from 23°C to 52°C over 150 seconds.
- Cold Stimulation: A defined, non-hazardous intradermal cold stimulus with decreasing temperature from 23°C to 4°C over 150 seconds.
- Acid stimulation: A defined, non-hazardous intradermal acid stimulus delivering a linear pH decrease from 7.2 to 5.4 over 110 seconds.
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.
- Conditions
- Pain, Acute Pain, Healthy Volunteer Study
- Being tested
- Suzetrigine, Lidocaine (drug), Control Solution
- Keywords
- Suzetrigine, VX-548, NaV1.8 Inhibitor, Sodium Channel Blocker, Selective NaV1.8 Antagonist, Microdosing, Intracutaneous injection, Experimental Pain Models, Human Pain Models, Capsaicin-induced pain, Thermal pain (Heat and Cold), Mechanical pain, Electrical stimulation, Acid-induced pain, Nociception
- Medical subject headings
- Pain, Acute Pain, Common Cold
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
SuzetrigineDrug
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.
Lidocaine (drug)Drug
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.
Control SolutionDrug
A control solution mimicking extracellular fluid. It is administered via intracutaneous injection at the site of pain induction.
| Study group | Role | What they receive |
|---|---|---|
| Suzetrigine | Experimental | 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). Receives: Drug: Suzetrigine |
| Lidocaine | Active comparator | 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). Receives: Drug: Lidocaine (drug) |
| Control solution | Placebo comparator | 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). Receives: Drug: Control Solution |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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).
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 150 seconds
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Apr 2026
- Study start21 Apr 2026
- Primary completion9 Jun 2026
- Study completion9 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PainStudies of the same condition, open and under way.
- More trials run by Medical University of ViennaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 67 participants (actual)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Stefan Heber, Medical University of Vienna
- Investigators
- Michael J.M. Fischer, Professor, Principal investigator, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07511400
- Sponsor's protocol ID
- EK1933/2025
- Status last verified
- Jun 2026
- First submitted
- 28 Mar 2026
- Last updated
- 24 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- 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.
Study at a glance
From the registry record, last updated by the sponsor on 24 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Role of NaV1.8 in Human Pain Models - a Randomized, Placebo-controlled Crossover Microdosing Trial
- ClinicalTrials.gov ID
- NCT07511400
- Acronym / sponsor ID
- EK1933/2025
- Conditions
- Pain, Acute Pain, Healthy Volunteer Study
- Keywords
- Suzetrigine, VX-548, NaV1.8 Inhibitor, Sodium Channel Blocker, Selective NaV1.8 Antagonist, Microdosing, Intracutaneous injection, Experimental Pain Models
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 67 participants (actual)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- 21 Apr 2026 (actual)
- Primary completion
- 9 Jun 2026 (actual)
- Study completion
- 9 Jun 2026 (actual)
- First posted
- 6 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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:
- Electrical stimulation: Brief electrical pulses delivered onto the skin.
- Mechanical stimulation: A standardised "pin-prick" stimulation of the skin.
- Chemical stimulation: An injection of fluid containing capsaicin (the active component of chilli peppers) superficially into the skin.
- Heat stimulation: An injection of hot fluid superficially into the skin.
- Cold stimulation: An injection of cold fluid superficially into the skin.
- Acid stimulation: An injection of acidic fluid superficially into the skin.
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.
Detailed description
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:
- Electrical Stimulation: Epicutaneous delivery of 5-pulse trains (0.6 ms duration) at 1.5 minutes post-injection.
- Mechanical Stimulation: Suprathreshold pin-prick stimulation using a standardised device at 1.5 minutes post-injection.
- Chemical Stimulation: Intradermal injection of 7.6 ng capsaicin to trigger a transient burning pain sensation.
- Heat Stimulation: A defined, non-hazardous intradermal heat stimulus with increasing temperature from 23°C to 52°C over 150 seconds.
- Cold Stimulation: A defined, non-hazardous intradermal cold stimulus with decreasing temperature from 23°C to 4°C over 150 seconds.
- Acid stimulation: A defined, non-hazardous intradermal acid stimulus delivering a linear pH decrease from 7.2 to 5.4 over 110 seconds.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Suzetrigine | Experimental | Drug: SuzetrigineParticipants 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). |
| Lidocaine | Active comparator | Drug: Lidocaine (drug)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). |
| Control solution | Placebo comparator | Drug: Control SolutionParticipants receive intracutaneous injections of control solution (negative control) before or during experimental pain induction across six different modalities (electrical, mechanical, capsaicin, heat, and cold). |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (9 listed)
- Age between 18 and 70 years
- Full legal capacity Exclusion criteria
- Participant of another study, ongoing or within the last 4 weeks
- Medication intake (except contraception) or drug abuse
- Female subjects: Positive pregnancy test or breastfeeding
Key exclusion criteria (0 listed)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| SuzetrigineA 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. | Drug | Suzetrigine |
| Lidocaine (drug)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. | Drug | Lidocaine |
| Control SolutionA control solution mimicking extracellular fluid. It is administered via intracutaneous injection at the site of pain induction. | Drug | Control solution |
Primary outcome
Pain Intensity: Electrical stimulation
Time frame: 1.5 minutes post-injection.
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.
Geometric Mean Pain Intensity: Mechanical stimulation
Time frame: 1.5 minutes post-injection.
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).
Area Under the Curve (AUC): Capsaicin injection
Time frame: From injection until 0 pain for 30 seconds.
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.
Area Under the Curve (AUC): Acid injection
Time frame: 110 seconds
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.
Area Under the Curve (AUC): Heat injection
Time frame: 150 seconds
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.
Area Under the Curve (AUC): Cold injection
Time frame: 150 seconds
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.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Jun 2026.
- Individual participant dataSharing planned: 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.
Related trials for Pain
Not yet recruiting
Effect of Stress Ball Use During Femoral Arterial Sheath Removal After Coronary Angiography
Femoral Arterial Sheath Removal, Stress Ball
Recruiting
Empowered Relief® for Cancer Survivors With Chronic Pain
Chronic Pain Due to Cancer, Pain Catastrophizing
RecruitingPhase 4
ESP Blocks for Posterior Spinal Fusion
Postoperative Pain
RecruitingObservational study
Pain Phenotypes in Individuals With Multiple Sclerosis
Multiple Sclerosis, Chronic Pain
Not yet recruiting
Effects of Hip Hinge Exercises on Pain, Range of Motion and Functional Disability in Non-specific Low Back Pain.
Low Back Pain
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Michael J.M. Fischer, Professor principal investigator
Medical University of Vienna
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Suzetrigine and Lidocaine (drug) in people with Pain and Acute Pain, run by Medical University of Vienna at 1 site in Austria.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 0 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 24 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Austria. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Pain Intensity: Electrical stimulation (time frame: 1.5 minutes post-injection.). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Jun 2026.