Carbidopa

As Parkinson's disease is a common degenerative disease of the nervous system in middle-aged and elderly people, levodopa replacement therapy is a clinically recognized core regimen. However, levodopa is easily decomposed by decarboxylase in the periphery, and only about 1% of it can enter the central nervous system to exert pharmacological effects, which also easily causes adverse reactions such as gastrointestinal reactions and dyskinesia. Carbidopa, as an aromatic amino acid decarboxylase inhibitor, cannot cross the blood-brain barrier by itself. When used in combination with levodopa, it can specifically inhibit the peripheral decarboxylation reaction of levodopa and increase the concentration of levodopa entering the central nervous system, which not only reduces the dosage of levodopa, but also lowers the incidence of peripheral adverse reactions. It is an indispensable compatibility component in levodopa compound preparations, and is widely used in the long-term treatment of patients with idiopathic Parkinson's disease and symptomatic Parkinsonism.

At present, the global carbidopa market size maintains a steady growth. In 2023, the global market size was approximately USD 210 million, with a compound annual growth rate maintained at around 3.2%. The growth momentum mainly comes from the increase in the global prevalence of Parkinson's disease, the expansion of the elderly population and the increase in the clinical application penetration rate of compound preparations. The Chinese market accounts for approximately 17% of the total global market size. In the current supply pattern, generic drugs account for more than 85%, while original research products only occupy the high-end market share. With the expansion of the coverage of the centralized procurement policy, the market share of carbidopa generic drugs still has room for further improvement, and the demand for upstream API also increases steadily accordingly. Unless otherwise specified, the above data are derived from public industry statistics.

The original research enterprise of carbidopa is Merck Sharp & Dohme, and its original research product is sold under the trade name Sinemet, which is a compound preparation of carbidopa and levodopa. Its core compound patent expired globally in 1994. At present, the main dosage form of the original research product on the market is tablet, and the conventional specifications include two types: carbidopa 25mg/levodopa 100mg and carbidopa 50mg/levodopa 200mg, which have been included in the FDA Reference Listed Drug Catalog, and also included in the *Catalog of Reference Preparations for Chemical Drugs* of China. In terms of domestic API registration, as of now, 6 enterprises have obtained A status for their carbidopa APIs through CDE registration, and more than 30 varieties of carbidopa and levodopa compound preparations have been approved for marketing. (Data as of June 2025, please refer to the official website of CDE for the latest information.)

CATO can provide a full set of carbidopa impurity reference standards, covering all research dimensions such as synthetic process impurities and degradation impurities. Most of the products are in stock, and in-stock products ordered before 16:00 can be shipped on the same day. All reference standards meet the requirements of multiple regulatory systems such as Chinese Pharmacopoeia and FDA, and can fully meet the use requirements of different scenarios such as API R&D, quality research, registration and declaration.