Primidone

Epilepsy is a common chronic neurological disease, with more than 9 million patients in China, of which approximately 30% are refractory cases, and there is a long-term clinical demand for broad-spectrum antiepileptic drugs. Primidone is a barbiturate antiepileptic drug, which is metabolized in vivo into two active products, phenobarbital and phenylethylmalonamide. It exerts its effect by reducing the sodium ion permeability of the neuronal cell membrane and inhibiting the spread of high-frequency abnormal discharges. It is suitable for monotherapy or combination therapy of tonic-clonic seizures, simple partial seizures and complex partial seizures of epilepsy, and can also be used for symptom control of essential tremor and senile tremor. It is a classic second-line drug for antiepileptic treatment in adults and children.

At present, the global market size of antiepileptic drugs exceeds 25 billion US dollars. As a mature variety that has been on the market for many years, primidone has an annual market size of approximately 120 million US dollars, with a stable growth trend, and the demand is mainly concentrated in primary medical institutions and the combination therapy scenario of refractory epilepsy. In terms of the domestic market, primidone is included in the National Essential Medicine List. At the current stage, there are fewer than 5 approved preparation manufacturers, and the supply of APIs has long been dependent on imports. With the improvement of the essential medicine allocation requirements, the R&D enthusiasm for domestic generic drugs has increased, and the supply gap of upstream APIs has gradually emerged.

The original developer of primidone is Bayer AG of Germany, with the original brand name Mysoline, and the core compound patent expired globally in 1982. The original marketed dosage form is tablet, with specifications of 50mg and 250mg, which has been included in the FDA Reference Listed Drug Catalog and the China Listed Drug Catalog. As of the search time point, there is no domestically produced primidone API approved for marketing in China, and only one application registration information of imported API is publicly displayed on the CDE API registration platform, and all approved primidone preparations in China are imported varieties. (Data as of July 2025, please refer to the official CDE website for the latest information)

In response to the R&D and quality control needs of primidone generic drugs, CATO provides a full set of impurity reference standards for this API, which can cover the needs of the whole research path including synthetic process impurities and degradation impurities. Most of the products are in stock, and in-stock products ordered before 16:00 will be shipped on the same day. All reference standards comply with the regulatory requirements of the Chinese Pharmacopoeia and the FDA, and can be directly used for structural confirmation, content determination, stability studies and other related tests.