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Study on Esketamine for Long-term Pain Relief in Patients with Complex Regional Pain Syndrome

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying Complex Regional Pain Syndrome (CRPS), a condition that causes persistent pain, usually in an arm or leg, following an injury. The study is investigating the effects of a medication called esketamine hydrochloride, which is administered as a solution for injection. The medication is provided in two different strengths, 25 mg/ml and 5 mg/ml, under the brand name Ketanest® S. The purpose of the study is to determine if a series of esketamine infusions given every two weeks for three months is as effective as the standard treatment, which involves a continuous administration of esketamine over six days in a clinical setting.

Participants in the study will receive esketamine through an intravenous infusion, which means the medication is delivered directly into the bloodstream through a vein. The study will last for a total of three months, during which participants will receive the infusions in a day treatment setting. The researchers aim to assess the impact of this treatment on pain levels and other symptoms associated with CRPS. The study will also monitor any side effects that may occur during the treatment period.

Throughout the study, participants' pain intensity will be measured using a simple scale, and the effects of the treatment on inflammation and other symptoms will be evaluated. The study will also look at how the treatment affects the need for other pain medications and any changes in CRPS symptoms over time. The goal is to provide valuable information on the effectiveness and safety of esketamine infusions for managing CRPS, potentially offering a new approach to treatment for those affected by this challenging condition.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes verifying age, diagnosis of complex regional pain syndrome (CRPS) according to the Budapest Criteria, and comprehension of the Dutch language.

  2. Step 2

    Treatment schedule

    The treatment involves receiving esketamine hydrochloride through intravenous infusion. The medication is administered in a day treatment setting every two weeks for a duration of three months.

    Two formulations of the medication are used: Ketanest® S 25 mg/ml and Ketanest® S 5 mg/ml, both as solutions for injection.

  3. Step 3

    Monitoring and evaluation

    Throughout the study, pain intensity is measured using the Numerical Rating Scale (NRS). This includes the current pain level and the average pain level over the last 24 hours.

    Additional assessments include monitoring for any side effects such as changes in mood, vision issues, nausea, sedation, and others.

  4. Step 4

    Follow-up assessments

    Follow-up assessments are conducted to evaluate the effects of the treatment on pain and inflammation. This includes measuring specific markers in the blood and assessing changes in pain perception.

    The study also evaluates the reduction in pain medication usage and changes in CRPS symptoms over time.

  5. Step 5

    Completion of study

    The study is expected to conclude by October 2026. Final assessments will be conducted to determine the long-term effects of the treatment on pain management and CRPS symptoms.

Who can join the trial?

6 criteria

  • Must be **18 years or older**.
  • Must meet the new **International Association for the Study of Pain (IASP) diagnostic criteria** for Complex Regional Pain Syndrome (CRPS), known as the "Budapest Criteria," or have met the criteria for "CRPS with Remission of Some features." This means the patient has been diagnosed with CRPS according to specific guidelines.
  • Must be **willing and capable** to participate in the study. This means the patient agrees to join the study and is able to do so.
  • Must have CRPS in **one upper limb** (like an arm) and/or **one lower limb** (like a leg).
  • Must be treated in an **elective setting**, which means the treatment is planned in advance and not an emergency.
  • Must have an **adequate understanding of the Dutch language**. This means the patient can understand and communicate in Dutch well enough to follow the study instructions.

Who cannot join the trial?

3 criteria

  • Patients who are not diagnosed with Complex Regional Pain Syndrome cannot participate. This is a condition that causes long-lasting pain, usually in an arm or leg, after an injury.
  • Patients who are younger than 18 years old or older than 65 years old cannot participate.
  • Patients who are part of a vulnerable population, meaning they might need special protection or care, cannot participate.
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Investigated drugs

Esketamine is being studied for its potential to help manage long-term pain in individuals with Complex Regional Pain Syndrome (CRPS). In this trial, esketamine is given through an intravenous infusion. The study aims to compare the effectiveness of esketamine infusions given every two weeks over three months in a day treatment setting to the standard treatment, which involves a continuous administration over six days during a clinical admission. The goal is to determine if the less intensive treatment is just as effective as the standard approach.

What is already known about the treatment

Esketamine – Esketamine is administered intravenously, typically in a clinical setting, where it is given as a series of infusions. It is currently being studied for its effectiveness in treating complex regional pain syndrome, with ongoing research to determine its long-term benefits. The main therapeutic use of esketamine in this context is to manage chronic pain that is difficult to treat with other medications. At the molecular level, esketamine works by blocking NMDA receptors in the brain, which are involved in pain perception and mood regulation. It is classified pharmacologically as a dissociative anesthetic, and it is known for its rapid-acting antidepressant effects in other medical uses.

Investigated diseases

Complex Regional Pain Syndrome – This is a chronic pain condition that typically affects one limb, often after an injury. It is characterized by prolonged or excessive pain and changes in skin color, temperature, and swelling in the affected area. The pain is often described as burning or throbbing and may be accompanied by sensitivity to touch or cold. Over time, the affected limb may experience changes in skin texture, hair and nail growth, and muscle weakness or atrophy. The exact cause of this syndrome is not well understood, but it is believed to involve abnormal responses of the nervous system. Symptoms can vary in intensity and duration, and they may spread to other parts of the body.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-511877-31-00Protocol codeNL77785.078.21Estimated enrolment60 patientsSponsorErasmus Universitair Medisch Centrum Rotterdam (Erasmus MC)

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