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Study of Pyridoxal Phosphate for Treatment of Seizures in Patients with PNPO Deficiency

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What is this trial about?

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

This study involves patients with a rare condition called Pyridox(am)ine 5'-Phosphate Oxidase (PNPO) deficiency, which causes seizures that are sudden episodes of uncontrolled electrical activity in the brain. The treatment being studied is MC-1, which is a tablet form of pyridoxal phosphate, a substance that the body normally makes from vitamin B6. People with this deficiency cannot produce enough of this substance on their own, which leads to seizures. The study will also use other antiepileptic medications, which are drugs used to prevent or control seizures.

The purpose of this study is to find out if MC-1 works well for long-term treatment of patients who have confirmed PNPO deficiency. Patients taking part in the study will receive MC-1 tablets by mouth over a period of up to one year. The study will look at whether this treatment helps control seizures and reduces the risk of death compared to patients who do not receive any treatment with pyridoxal phosphate. The study will also track how often seizures occur during the treatment period.

During the study, patients will take MC-1 tablets multiple times daily, similar to how they may have been taking other forms of this vitamin before. The treatment can last up to 52 weeks, with a maximum daily dose of 3 grams. The study is designed for patients aged 2 years and older who have had their condition confirmed through genetic testing and whose seizures are usually controlled with oral treatment.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Treatment with MC-1 tablet

    During this study, you will receive MC-1, which contains pyridoxal phosphate as the active substance. This medication is designed to help control seizures in patients with PNPO deficiency, a rare genetic condition that affects how the body processes certain forms of vitamin B6.

    The medication will be provided in tablet form and will be taken by mouth.

    You will receive MC-1 as a chronic treatment, meaning it is intended for long-term use to manage your condition.

    The study does not specify the exact dosage or frequency of administration in the available information. Your treating physician will determine the appropriate dose for you based on your individual needs.

  2. Step 2

    Study participation period

    The study will evaluate how well MC-1 works for the chronic treatment of your condition over a period of time.

    The main evaluation point will occur at 12 months after you begin treatment.

    During this time, the study will monitor important health outcomes and the frequency of seizures you may experience.

  3. Step 3

    Monitoring during the study

    Throughout the study, your health status will be monitored, including any seizures that may occur.

    The study will track the frequency of seizures, including any severe or prolonged seizure episodes.

    Your overall health and response to the treatment will be assessed during the study period.

Who can join the trial?

8 criteria

  • You must have confirmed PNPO deficiency, which is a rare genetic condition that affects how the body processes certain forms of vitamin B6, confirmed through genetic testing (a test that looks at your genes or DNA)
  • Your seizures (sudden uncontrolled electrical activity in the brain causing changes in behavior, movements, or consciousness) must be typically controlled with P5P (a specific form of vitamin B6 called pyridoxal 5'-phosphate) taken by mouth
  • You must be taking multiple doses of P5P each day to control your seizures
  • You must have been receiving P5P treatment for at least 30 days
  • You can be male or female
  • You must be 2 years of age or older
  • You can participate if you previously tried pyridoxine (another form of vitamin B6) and it did not work for you, as long as you have stopped taking pyridoxine for at least 24 hours
  • You must provide written permission to participate in the study, or if you are under 18 years old, your parent or guardian must provide written permission on your behalf

Who cannot join the trial?

3 criteria

  • The source data does not provide specific exclusion criteria for this clinical trial
  • If you are interested in participating, the research team will need to review your complete medical history to determine if you can safely take part in this study
  • General factors that might prevent participation could include other medical conditions, certain medications you are taking, or other health concerns that need to be evaluated by the study doctors
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Investigated drugs

MC-1 is an oral medication being tested for the treatment of PNPO deficiency. PNPO deficiency is a rare genetic condition that affects how the body processes vitamin B6, which is important for brain function. This medication is designed to help manage the symptoms of this condition when taken by mouth over a long period of time.

What is already known about the treatment

MC-1 – MC-1 is an oral medication currently being studied in clinical trials for treating seizures in patients with a rare genetic condition called PNPO deficiency, where the body cannot properly process certain forms of vitamin B6. The medication works by providing a form of vitamin B6 that can bypass the defective enzyme (PNPO) that normally converts vitamin B6 into its active form needed for brain function and seizure control. It belongs to the class of vitamin supplements and enzyme cofactor replacements. The main goal of the ongoing research is to determine how well MC-1 works as a long-term treatment to control seizures in people with this rare metabolic disorder.

Investigated diseases

Pyridox(am)ine 5'-Phosphate Oxidase Deficiency – A rare genetic disorder caused by mutations in the PNPO gene, which affects the body's ability to produce an enzyme needed to convert vitamin B6 into its active form. Without this enzyme, the brain cannot properly produce important chemical messengers that help nerve cells communicate. The condition typically appears in newborns or early infancy, though it can sometimes develop later. Affected individuals experience seizures that begin soon after birth and do not respond to standard seizure medications. The seizures can be of various types and may occur very frequently, sometimes progressing to prolonged seizure episodes. This enzyme deficiency disrupts normal brain development and function, leading to ongoing neurological problems if not properly managed.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522346-46-00Protocol code16002Estimated enrolment3 patientsSponsorMedicure International Inc.

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