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Comparing Abobotulinumtoxin A and Onabotulinumtoxin A for Adults with Upper Limb Spasticity

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 study is looking at upper limb spasticity, which is a condition where muscles in the arm become stiff and tight, making it difficult to move the arm normally. This can happen due to various causes, including stroke. The study will compare two treatments called Dysport and Botox, which are both medicines that contain a substance called botulinum toxin type A. These medicines are given as injections directly into the affected muscles in the arm to help reduce the muscle stiffness and improve movement.

The purpose of this study is to show that Dysport is as safe as Botox when used to treat adults with upper limb spasticity by looking at side effects that occur during the first 12 weeks after the injection. Both medicines will be injected into specific muscles in the arm, including muscles that control the wrist, fingers, and elbow. The study will use a crossover design, which means that participants will receive both treatments at different times during the study, allowing doctors to compare how well each medicine works for the same person. The total amount of medicine given will be 900 units for Dysport or 360 units for Botox, depending on which treatment is being given at that time.

During the study, doctors will check for any unwanted effects or side effects that may occur after the injections. They will also measure how well the muscles respond to treatment by checking muscle stiffness, how well the arm functions in daily activities like dressing and hygiene, and whether there is any pain. These measurements will be taken at several visits over a period of up to 24 weeks. The study will also look at how long the treatment effects last before another injection is needed and will ask participants about their overall quality of life and how they feel about their treatment response.

The research process

The trial runs in 9 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment with first medication

    Your affected arm will be treated with an injection of botulinum toxin type A. This medication works by relaxing tight muscles. The injection will be given directly into specific muscles in your upper limb using the intramuscular route, which means the medication is injected into the muscle.

    The medication will be injected into the following muscles: flexor carpi radialis, flexor carpi ulnaris, flexor digitorum profundus, flexor digitorum superficialis, and biceps brachii. These are muscles in your forearm and upper arm that control finger, wrist, and elbow movement.

    You will receive either 900 Units of abobotulinumtoxinA (Dysport) or 360 Units of onabotulinumtoxinA (Botox) as a total dose. The specific medication you receive will be determined randomly, and neither you nor your doctor will know which one you are receiving during this treatment cycle.

  2. Step 2

    Follow-up assessment at week 1

    At 1 week after your injection, you will have an assessment visit.

    Your muscle tone will be measured using the Modified Ashworth Scale, which assesses the stiffness in your finger, wrist, and elbow muscles.

    Your function and pain will be evaluated using the Disability Assessment Scale, which looks at how the treatment affects daily activities such as dressing, hygiene, limb position, and pain.

    Your doctor will provide a global assessment of how you are responding to treatment.

  3. Step 3

    Follow-up assessment at week 4

    At 4 weeks after your injection, you will have another assessment visit.

    The same evaluations from week 1 will be repeated: muscle tone measurement, function and pain assessment, and doctor's global assessment of treatment response.

    Your quality of life will be assessed using two questionnaires: the SF-12 (a general health questionnaire) and the SQoL-6D (a spasticity-specific quality of life questionnaire).

  4. Step 4

    Follow-up assessment at week 10

    At 10 weeks after your injection, you will have another assessment visit.

    Your muscle tone will be measured using the Modified Ashworth Scale for finger, wrist, and elbow muscles.

    Your function and pain will be evaluated using the Disability Assessment Scale.

    Your doctor will provide a global assessment of treatment response.

  5. Step 5

    End of first treatment cycle at week 12

    At 12 weeks after your first injection, the first treatment cycle will end.

    All assessments from previous visits will be repeated: muscle tone, function and pain, and doctor's global assessment.

    Your quality of life will be assessed again using the SF-12 and SQoL-6D questionnaires.

    Safety will be monitored throughout this period by tracking any treatment-emergent adverse events, which are any unwanted medical occurrences that happen after treatment.

  6. Step 6

    Second treatment with alternative medication

    You will receive a second injection of botulinum toxin type A. This time, you will receive the alternative medication that you did not receive in the first treatment cycle.

    If you received Dysport (900 Units of abobotulinumtoxinA) in the first cycle, you will now receive Botox (360 Units of onabotulinumtoxinA), or vice versa.

    The injection will be given in the same muscles as before: flexor carpi radialis, flexor carpi ulnaris, flexor digitorum profundus, flexor digitorum superficialis, and biceps brachii.

    The injection method remains the same, with medication delivered directly into the muscles.

  7. Step 7

    Follow-up assessment at week 16

    At 1 week after your second injection (approximately week 16 from the start), you will have an assessment visit.

    Your muscle tone will be measured using the Modified Ashworth Scale.

    Your function and pain will be evaluated using the Disability Assessment Scale.

    Your doctor will provide a global assessment of treatment response.

  8. Step 8

    Follow-up assessment at week 20

    At 4 weeks after your second injection (approximately week 20 from the start), you will have another assessment visit.

    The same evaluations will be performed: muscle tone measurement, function and pain assessment, and doctor's global assessment.

    This visit follows the same pattern as the week 4 assessment in the first treatment cycle.

  9. Step 9

    End of second treatment cycle at week 24

    At 12 weeks after your second injection (approximately week 24 from the start), the second treatment cycle will end.

    All final assessments will be completed: muscle tone using the Modified Ashworth Scale, function and pain using the Disability Assessment Scale, and doctor's global assessment.

    Your quality of life will be assessed one final time using the SF-12 and SQoL-6D questionnaires.

    Safety will continue to be monitored by tracking any treatment-emergent adverse events, adverse drug reactions, serious adverse events, and any events of special interest throughout this period.

    The duration of response will be measured based on when retreatment would be needed.

Who can join the trial?

11 criteria

  • You must be between 18 and 80 years old at the time you sign the consent form
  • You must be able to give your written permission to take part in the study and follow all the requirements
  • You must have stable muscle stiffness in your upper arm or hand (called spasticity) for at least 3 months, and only one arm needs treatment during the study
  • You may be new to treatment with botulinum toxin type A (a medicine used to relax stiff muscles) or you may have received it before for your arm stiffness
  • You must have a certain level of muscle stiffness measured on a scale, with a score of at least 2 in two muscle groups (one of these must be the main problem area) and at least 1 in another muscle group
  • You must have a disability score of at least 2 in the main problem area, meaning your arm stiffness affects at least one daily activity such as dressing, washing, arm position, or causes pain
  • You must need injections in all of these specific muscles: flexor carpi radialis, flexor carpi ulnaris, flexor digitorum profundus, flexor digitorum superficialis, and biceps brachii (these are muscles in your forearm and upper arm that control wrist, finger, and elbow movement)
  • The doctor must consider that a specific dose of the study medicine is appropriate for you
  • If you take medicines for muscle stiffness, blood thinning, or certain other medicines, you must have been on a stable dose for at least 3 months before joining the study and are expected to stay on the same dose throughout the study
  • If you are a man whose partner could become pregnant, you must agree to use effective birth control during the entire study
  • If you are a woman, you must not be pregnant or breastfeeding. You must either be unable to have children due to menopause (no periods for at least 1 year), surgical sterilization (at least 3 months before the study), or hysterectomy (removal of the uterus), or if you can have children, you must use effective birth control and have a negative pregnancy test before starting the study

Who cannot join the trial?

9 criteria

  • The study does not list specific reasons why patients cannot participate
  • Please note that general safety requirements and medical assessments will be used to determine if you are suitable for this study
  • Your doctor will review your complete medical history and current health condition to decide if you can take part
  • Certain medications or treatments you are currently receiving may affect your ability to participate
  • If you have received botulinum toxin (a medicine injected into muscles to reduce tightness) recently, you may need to wait before joining
  • Women who are pregnant or breastfeeding (nursing a baby) are typically not able to participate in studies like this
  • If you have allergies to the study medication or similar treatments, you may not be able to take part
  • Certain medical conditions affecting your nervous system (the brain, spinal cord, and nerves) or muscles may prevent participation
  • If you have difficulty understanding or following study instructions, this may affect your ability to participate
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Investigated drugs

  • AbobotulinumtoxinA

    (also known as Dysport) is a medication that is injected into muscles to help reduce muscle stiffness and spasms. It works by blocking the signals between nerves and muscles, which helps the muscles relax. In this study, it is being used to treat tightness and stiffness in the arm muscles of adults.

  • OnabotulinumtoxinA

    (also known as Botox) is another type of medication that is injected into muscles to reduce muscle stiffness and spasms. Like the first medication, it works by blocking nerve signals to help muscles relax. In this study, it is also being used to treat tightness and stiffness in the arm muscles of adults.

What is already known about the treatment

  • Dysport

    Dysport is an injectable medication containing abobotulinumtoxinA, a form of botulinum toxin type A, which is administered directly into affected muscles by a healthcare professional. It is an approved treatment used in medical practice for managing upper limb spasticity, a condition where muscles become stiff and difficult to control, often occurring after a stroke or due to other neurological causes. The medication works at the molecular level by blocking the release of a chemical messenger called acetylcholine at the junction between nerves and muscles, which temporarily relaxes the overactive muscles and reduces stiffness. Dysport belongs to the pharmacological class of neuromuscular blocking agents and neurotoxins, specifically used for therapeutic muscle relaxation.

  • Botox

    Botox is an injectable medication containing onabotulinumtoxinA, another form of botulinum toxin type A, which is administered through injections into specific muscles by a trained healthcare provider. It is a well-established treatment in clinical medicine used for various conditions including upper limb spasticity, where it helps reduce muscle stiffness and improve movement in patients who have experienced stroke or other conditions affecting muscle control. The drug functions at the molecular level by preventing the release of acetylcholine, a neurotransmitter that signals muscles to contract, thereby causing temporary muscle relaxation and decreased spasticity. Botox is classified as a neuromuscular blocking agent and belongs to the category of therapeutic neurotoxins used for medical purposes.

Investigated diseases

Upper Limb Spasticity – Upper limb spasticity is a condition characterized by increased muscle stiffness and involuntary muscle contractions in the arm, hand, wrist, elbow, and fingers. This disorder occurs when muscles remain constantly contracted, making it difficult to control movements and perform everyday activities. The condition can develop after various injuries or diseases affecting the brain or spinal cord, with stroke being one of the most common causes. People with upper limb spasticity experience tight muscles that resist stretching and may cause the affected limb to remain in abnormal positions. The severity of symptoms can vary from mild muscle tightness to severe rigidity that significantly limits arm function. Over time, persistent spasticity may lead to joint stiffness, pain, and reduced range of motion in the affected upper limb.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509196-16-00Protocol codeCLIN-52120-452Estimated enrolment464 patientsSponsorIpsen Pharma

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