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Study on Esflurbiprofen Topical System and Paracetamol for Pain Relief in Patients with Acute Ankle Sprains

Registered 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 the treatment of acute ankle sprains, which are injuries that occur when the ankle is twisted or turned in an awkward way, causing pain and swelling. The treatment being tested is called the Esflurbiprofen Topical System (EFTS), which is a patch applied to the skin that contains a medication known as esflurbiprofen. This medication is designed to help reduce pain and inflammation in the affected area. The study will compare the effectiveness of the EFTS patch to a placebo patch, which looks the same but does not contain the active medication.

The purpose of the study is to determine if the EFTS patch is better at reducing pain compared to the placebo patch in people with ankle sprains. Participants in the study will be randomly assigned to receive either the EFTS patch or the placebo patch. They will apply the patch to the affected area and will be monitored over a period of time to assess changes in their pain levels. The study will also involve the use of paracetamol, a common pain reliever, to help manage pain if needed.

Throughout the study, participants will be asked to report their pain levels and any changes they experience. The study aims to gather information on how well the EFTS patch works in reducing pain and improving the ability to move the ankle. The results will help determine if the EFTS patch is a safe and effective treatment option for people with ankle sprains.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and initial assessment

    Upon joining the study, you will undergo an initial assessment to confirm eligibility. This includes verifying that you have an acute ankle sprain of grade I, the injury location elicits pain during movement, and enrollment occurs within 6 hours of the injury.

    Your pain level will be measured using a Visual Analogue Scale (VAS), where you will rate your pain on a scale from 0 to 100 mm. A baseline score greater than 50 mm is required.

  2. Step 2

    Randomization and treatment allocation

    You will be randomly assigned to receive either the Esflurbiprofen Topical System (EFTS) or a placebo patch. The placebo patch looks identical to the EFTS but does not contain the active ingredient.

    The patch will be applied to the affected area for the duration of the study.

  3. Step 3

    Treatment period

    The treatment involves applying the patch to the injured ankle. The patch is a transdermal patch, meaning it delivers medication through the skin.

    You will be required to keep the patch on for a specified period, and the adhesive power of the patch will be assessed at various intervals.

  4. Step 4

    Pain assessment

    Your pain levels will be regularly assessed using the VAS at multiple time points: 6 hours, before bedtime on Day 1, and at 12, 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, and 168 hours.

    These assessments will help determine the effectiveness of the treatment in reducing pain during movement and at rest.

  5. Step 5

    Evaluation of treatment response

    The study will evaluate how quickly and effectively your pain is reduced. This includes measuring the time to a meaningful reduction in pain, defined as at least a 30% reduction from baseline, and an optimal reduction, defined as at least a 50% reduction.

    The time to complete resolution of pain during movement and at rest will also be recorded.

  6. Step 6

    Global efficacy assessments

    Both you and the study physician will provide global efficacy assessments at 48, 72, and 168 hours. This involves rating the overall response to the treatment on a scale from 0 (no response) to 4 (excellent response).

  7. Step 7

    Use of rescue medication

    If necessary, you may use rescue medication to manage pain, except during the first visit. The use of such medication will be recorded.

  8. Step 8

    Final assessment and conclusion

    At the end of the study period, a final assessment will be conducted to evaluate the overall effectiveness and safety of the treatment.

    The study will conclude with a review of any side effects or adverse reactions experienced during the trial.

Who can join the trial?

8 criteria

  • Must have an acute ankle sprain Grade I. This means a mild sprain of the ankle.
  • The injury must be in a location where pain-on-movement (POM) is felt during specific movements. POM means feeling pain when moving the injured area.
  • Must enroll in the study within 6 hours of the injury happening.
  • Must have a baseline Visual Analogue Scale (VAS) score for POM of the injured area greater than 50 mm on a 100 mm scale. The VAS is a tool used to measure pain intensity.
  • Must be an adult male or female patient.
  • Must be between the ages of 18 to 64 years, including those ages.
  • Must have given written informed consent. This means agreeing to participate in the study after being informed about it.
  • Must be in satisfactory health as determined by the study doctor based on medical history and a physical examination.

Who cannot join the trial?

10 criteria

  • Patients with any other **serious injury** to the ankle or foot.
  • Patients who have had **surgery** on the affected ankle in the past 6 months.
  • Patients with a **history of chronic pain** conditions.
  • Patients who are currently taking **pain medication** that cannot be stopped.
  • Patients with **allergies** to the study medication or similar medications.
  • Patients who are **pregnant** or **breastfeeding**.
  • Patients with **severe medical conditions** that could interfere with the study.
  • Patients who have participated in another **clinical trial** in the last 30 days.
  • Patients with **mental health conditions** that could affect their ability to participate.
  • Patients who are unable to **understand** or **follow** the study instructions.
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Investigated drugs

Esflurbiprofen Topical System (EFTS) is a treatment applied directly to the skin over the affected area. It is designed to help reduce pain and inflammation in people who have sprained their ankles. The medication works by delivering a pain-relieving substance directly to the site of the injury, which can help decrease the discomfort and swelling associated with the sprain. The goal of using this topical system is to provide quick relief from pain when moving the ankle, making it easier for patients to go about their daily activities while their injury heals.

What is already known about the treatment

Esflurbiprofen Topical System (EFTS) – This medication is applied directly to the skin as a topical system, specifically designed for treating pain from acute ankle sprains. It is currently being studied in clinical trials to assess its effectiveness and safety compared to a placebo. The main use of this medication is to provide short-term relief from pain associated with ankle sprains. At the molecular level, it works by reducing the production of substances in the body that cause inflammation and pain. It belongs to a class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs).

Investigated diseases

Acute ankle sprains grade I – An acute ankle sprain grade I is a mild injury to the ligaments of the ankle, typically caused by twisting or rolling the foot. This type of sprain involves stretching or slight tearing of the ligament fibers, leading to pain and swelling. The affected area may be tender to touch, and there might be some stiffness or difficulty in moving the ankle. Bruising is usually minimal or absent, and the ankle remains stable. Over time, the pain and swelling gradually decrease, allowing for improved movement. Recovery involves the gradual return to normal activities as the ligament heals.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-513063-45-00Protocol codeTK-254RX-0301Estimated enrolment110 patientsSponsorTeikoku Seiyaku Co. Ltd.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

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