Withdrawal of Tiratricol Treatment in Males With Monocarboxylate Transporter 8 Deficiency (MCT8 Deficiency)

You may not qualify if:

• Major illness or recent major surgery unrelated to MCT8 deficiency (in the principal investigator's judgement), defined as:
• Conditions requiring repeated hospitalizations that are likely to confound ability to participate in the trial.
• Major illness in the 3 months prior to the Screening Visit that is likely to confound the ability of the participant to participate fully within the trial and/or confound the assessment of serum total T3 and/or safety.
• Major surgery within the 3 months prior to the Screening Visit or planned to take place during the study, including but not limited to major abdominal/thoracic/neurosurgical procedures.
• Major/minor abdominal and/or maxillofacial surgery that may inhibit the administration and/or absorption of study drug.
• Body weight \<10 kg at the Screening Visit.
• Patients who are participating, or intend to participate, in other therapeutic and/or interventional clinical studies during the study period.
• History of allergic reactions to components of tiratricol or any excipients in the investigational product (IP).
• Participants with any contra-indication for treatment with tiratricol or any excipients in the IP.
• Participants who have used other T3 analogues, levothyroxine, propylthiouracil, or other antithyroid medications within 6 weeks of screening.
• Randomization Criteria:
• In addition to the eligibility criteria, participants must meet further criteria at the time of randomization to enter the Randomized Treatment Period.
• Confirmation that the "Stable Dose Criterion" has been met.
• Confirmation that participant is at least 4 years of age at the time of randomization.