Novel L-Thyroxine Radioiodine Marker and Process for Its Preparation

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The invention describes a novel radiolabeled L-thyroxine (thyroid hormone) marker, specifically labeled at the 3-position of its inner aromatic ring with radioactive iodine. This marker is produced through an efficient, multistep synthetic process starting from 3,5-diiodo-L-thyronine. The resulting radioiodinated thyroxine demonstrates increased chemical stability and higher specific activity compared to traditional markers labeled on the outer ring. This stability makes it especially suitable for applications in nuclear medical imaging (such as PET and SPECT) and various in vitro and ex vivo assays requiring radioactive thyroid hormone tracers.

Use CasesContent extracted from patent full text and abstract with AI.

• Non-invasive imaging of thyroid hormone distribution and metabolism in vivo using PET or SPECT scans.
• Diagnosis and monitoring of thyroid-related disorders and syndromes, including Allan-Herndon-Dudley syndrome (AHDS) and other conditions involving thyroid hormone transport.
• In vitro diagnostic tests or assays for measuring free or total thyroxine levels in biological fluids.
• Pharmacokinetic and metabolic studies of thyroid hormones.
• Evaluation of thyroid hormone uptake and cellular transport in research or clinical settings.

BenefitsContent extracted from patent full text and abstract with AI.

• Greater stability of the radiolabel in vivo and in vitro, reducing measurement artifacts and increasing reliability of imaging or assay results.
• High specific activity allows for significant signal detection even at low (physiological) concentrations of the marker.
• Improved efficiency and reproducibility in synthesis, resulting in higher yields of the radiomarker.
• Applicable to multiple radioactive iodine isotopes, providing flexibility for different imaging or experimental requirements.
• Enabled study of all thyroid hormone deiodinase pathways by selective labeling, offering more comprehensive diagnostic and research applications.

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Patent Abstract

The present invention relates to a multistage synthesis process proceeding from 3,5-diiodo-L-thyronine for synthesis of an L-thyroxine radiolabelled in the 3 position on the inner ring. The present invention further relates to specific intermediates in the synthesis process of the invention, to the radiolabels obtainable and to the use of the radiolabels in nuclear-medical imaging methods and in in vitro and ex vivo applications.