Liothyronine

Hypothyroidism is a common endocrine disease, and conventional levothyroxine replacement therapy has limited efficacy in some patients with thyroid hormone resistance syndrome and myxedema coma. Liothyronine, a synthetic triiodothyronine (T3) class of thyroid hormone drug, can directly bind to thyroid hormone receptors in the nucleus, and exert effects of promoting substance metabolism, maintaining body growth and development, and regulating sympathetic excitability more rapidly. It is mainly used clinically for the emergency treatment of severe hypothyroidism and levothyroxine combined replacement therapy regimens, and can also be applied in thyroid suppression tests to diagnose thyroid diseases, providing a more accurate medication option for severe and special patient groups with thyroid diseases.

The global market size of liothyronine preparations maintains steady growth. In 2023, the market size was approximately USD 420 million, with a compound annual growth rate of about 3.8%. The growth mainly comes from the expansion of medication demand for rare disease indications and the increase in the penetration rate of refined treatment for the elderly hypothyroidism population. In terms of the domestic market, liothyronine has not yet been included in the national centralized procurement. The original research product accounts for about 85% of the market share, the number of approved domestic generic drugs is small, there has been a certain gap in the supply of API for a long time, and the demand for domestic generic drug R&D and supporting API registration continues to rise.

The original research enterprise of liothyronine is GlaxoSmithKline (GSK), and the original brand name is Cytomel (also known as 赛治 in Chinese, with the brand name Triostat in some regions). Its core compound patent expired globally in 1987. The main marketed dosage form of the original research product is tablet, with specifications including 5μg, 25μg and 50μg, which has been included in the FDA Reference Listed Drug Catalog and China's *Catalog of Reference Preparations for Chemical Drugs*. As of September 2024, no enterprise in China has obtained the A-status registration number of liothyronine API. Only one domestic enterprise has obtained the marketing approval of liothyronine sodium generic preparation, and the original preparation has not been approved for import in China. (Data as of September 2024, please refer to the official website of CDE for the latest information)

CATO can provide a full set of impurity reference standards for liothyronine, most of which are in stock. For in-stock products, orders placed before 16:00 will be shipped on the same day. The products meet the compliance requirements of multiple regulations such as the Chinese Pharmacopoeia and FDA, and can fully meet the full-process needs of API R&D, quality research and generic drug declaration.