Seoul, April 14 : Celltrion, a major South Korean biopharmaceutical firm, on Monday said it has obtained an interchangeability approval for its biosimilar drug for autoimmune disease treatment in the United States.

The US Food and Drug Administration (FDA) designated Celltrion's biosimilar Yuflyma as interchangeable medicine for its original drug Humira in the US, Yonhap news agency reported.

Interchangeability approval is a designation given to drugs that can be substituted for another drug at pharmacies without doctors' prescriptions.

The global Humira market reached 12.59 trillion won ($8.99 billion) last year, with nearly 80 percent of the sales in the U.S. market, the company said in a statement.

Celltrion expects the interchangeability approval will help drive up its Yuflyma sales in the world's biggest pharmaceutical market.

Celltrion has significantly expanded its global biosimilar lineup, increasing the number of approved products from six to 11.

It aims to commercialise 22 biosimilar products by 2030, when the targeted global market size is expected to nearly double to 261 trillion won from 138 trillion won this year.

Earlier, the company said that Celltrion Chairman Seo Jung-jin will purchase 50 billion won worth of Celltrion shares from May 9, using his private funds, while Celltrion Holdings and Celltrion Skincure plan to spend 100 billion won and 50 billion won, respectively, to buy the stocks, the company said.

"The chairman made the decision to show his commitment to responsible management and enhancing shareholders' value," the company said, adding the planned purchases will be made during trading hours.

Celltrion Holdings, the holding company of Celltrion Group, has a 21.96 per cent stake in Celltrion, while Celltrion Skincure owns a 1.89 per cent stake in the pharmaceutical firm.

The company has been in the process of buying back its own shares worth 350 billion won since early this year while planning to cancel more than 800 billion won worth of stocks this year.

/IANS