Human Experimental Models of Pain (HEMP)

What this study involves

The registry does not currently label this study as recruiting. Ask about its status before planning a screening visit.

Study type

Interventional

Phase

Not applicable

Age range

18 years - 100 years

Sex eligible

All sexes

Healthy volunteers

Accepted

Participants

25 Estimated

These are starting points, not an eligibility decision. The research team must review the full requirements.

About the research

This pilot study will test an innovative way to establish how pain medicines provide analgesia in healthy adults. The study uses a group of short, controlled pain tests to look at different types of pain responses in the body. The main goal is to find out if this testing approach can show the pain-relieving effects of 2 medicines, pregabalin and naproxen versus placebo, and show how they provide relief of different types of pain.

The study hypothesis is that this pain testing approach administered as a battery would be able to tell the difference between a medicine that works mainly in the brain and spinal cord (pregabalin) and a medicine that works mainly on inflammation in body tissues (naproxen).

Up to 25 healthy adults will take part. Each participant will receive all 3 study treatments, pregabalin, naproxen, and placebo, administered in random order during separate study periods. The order will be assigned by chance. Neither the participant nor the study team will know which treatment is given at each visit.

The study includes several experimental pain tests. These include:

a heat and capsaicin skin test that causes short-term skin sensitivity,

a UVB light test that causes a temporary sunburn-like sensitivity, and

a cold pressor test, in which a hand is placed in very cold water for a short time.

Participants will also have sensory testing to measure how they feel touch, pressure, pinprick, warmth, heat, and cold. Blood samples will be collected to measure study drug levels. Urine samples, vital signs, and other safety checks will also be done.

Each treatment visit includes testing before and for several hours after taking the study drug. There will be a washout period of at least 48 hours between treatments. Total participation may last up to about 10 weeks.

This study is not expected to provide direct medical benefit to participants. The information learned may help researchers improve early testing of future pain treatments....

Who may be able to participate?

The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.

• INCLUSION CRITERIA:

For an individual to be eligible to participate in this study, they must meet all of the following criteria:

• Voluntarily consent to participate and provide written informed consent prior to the start of any study-specific procedures.
• Read and speak English fluently.
• State willingness to comply with all study procedures and availability for the duration of the study.
• Are not pregnant or breastfeeding.
• Are 18 or older years of age at screening.
• Have a skin type score between 2 and 5 (inclusive) on the Fitzpatrick Scale.
• Must correctly identify at least nine out of 12 temperatures (32 degrees Celsius, 38 degrees Celsius, 44 degrees Celsius, and 50 degrees Celsius, each presented three times) during the sensory discrimination test at screening.
• Provide a verbal pain rating between 4 and 9 (inclusive) during the intradermal capsaicin challenge at screening. The study team will verify tolerability, and participants will continue only after it has been confirmed.
• During the cold pressor test at screening, provide a verbal pain rating between 4 and 9 (inclusive) and keep one hand completely immersed in ice-cold water (1-4 degrees Celsius) between 1 and 4 minutes (inclusive). The study team will verify tolerability, and participants will continue only after it has been confirmed.
• Are able to learn and perform all quantitative sensory testing QST procedures (see the separate QST manual).
• Have the ability to take oral medication and be willing to adhere to the study intervention regimen.

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this study:

• Have a history or presence of clinically significant cardiovascular, pulmonary, hepatic, renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurologic, oncologic, or psychiatric disease or any other condition that, in the opinion of the Investigator, would jeopardize the safety of the participant or the validity of the study results.
• Have alcohol or drug dependence (excluding nicotine and caffeine) within the past 2 years, as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision (DSM IV-TR) and/or participants who have ever been in a substance or alcohol rehabilitation program to treat their substance dependence are currently seeking such treatment.
• Have a clinically significant abnormal finding on the physical exam, medical history, or clinical laboratory results at screening.
• Have a history of psychotic reactions, a non-psychotic emotional disorder, or another mental illness that, in the opinion of the investigator, may affect the ability of the participant to participate in the study.
• Have recent history of suicidal ideation or suicidal behavior within the past 6 months, as assessed by the Columbia- Suicide Severity Rating Scale (C-SSRS) at screening (baseline version) or at check-in ( Since Last Visit version).
• Have a history of allergy or hypersensitivity to pregabalin or other gabapentinoids, naproxen or other NSAIDs, or another ingredient in the study drugs, or anything else that, in the opinion of the Investigator, could put the participant at risk.
• Have participated in another clinical trial (randomized participants only) within 30 days prior to the first dose of study medication.
• Use any prescription medication, except hormonal contraceptive or hormonal replacement therapy, from 14 days prior to the first dose of study medication until study participation has ended without evaluation and approval by the Investigator.
• Donate blood or plasma within 30 days prior to the first dose of study medication until the end of study participation. It is recommended that participants not donate blood or plasma until at least 30 days after their study participation has ended.
• Female participants who are currently pregnant or breastfeeding, or who are planning to become pregnant during the study or within 30 days after the last study drug administration.
• Show a positive urine alcohol test at screening.
• Have smoked or used tobacco- or nicotine-containing products within 30 days prior to the first dose of study treatment until the end of the study.
• Have an allergy to capsaicin or another capsaicinoid.
• Have a tattoo, excessive scarring or discoloration, keloid formation, or, at the Investigator s discretion, otherwise unhealthy skin (e.g., eczema, psoriasis, burn, and cut) at a QST site.
• Have a significant history of nerve injury or damage at a QST site, at the Investigator s discretion.
• Participants who report any stimulus as intolerable at any point during the screening procedures will be excluded from participation.

Treatment, groups and participation

The registry may describe treatments and study duration without a complete visit calendar. Ask the study team for the exact schedule, procedures, risks, costs and alternatives. Keep your usual care plan unless your treating clinician tells you otherwise.

Assignment

Random assignment

Masking

Triple masked

What researchers are measuring

Outcome measures describe what is being studied. They are not proof that a treatment works.

Primary measures

Secondary measures

Research locations (1)

The overall study status and a local site’s status can differ. Confirm that location’s availability before traveling.

1 locations

Study team and timeline

Lead sponsor

National Center for Complementary and Integrative Health (NCCIH)

Study start

Nov 15, 2026 Estimated

Primary completion

Dec 31, 2029 Estimated

Study completion

Dec 31, 2030 Estimated

First posted

Apr 24, 2026 Actual

Last updated

Nov 10, 2026 Actual

Official study contacts