Two major drug firms are competing to become the first South Korean maker of a new homegrown medication with annual sales of more than 50 billion won, a landmark for the local industry, sources said Tuesday.

Industry experts define as a blockbuster drug an extremely popular medicine that generates annual sales of at least 10 billion won ($8.6 million) for the company that produces it. No locally produced drug has posted annual sales of 50 billion won or more so far.

According to the sources, one of the candidates is LG Life Sciences Ltd. with its next generation diabetes treatment Zemiglo.

In the first three quarters of this year, sales of Zemiglo and its combination product Zemimet reached a combined 37.3 billion won, compared with 24.8 billion won for all of last year.

The company painted a rosy picture of sales for the current quarter. "In light of sales in October and November, annual sales are tipped to exceed 50 billion won, achieving the feat for the first time among locally produced new drugs," an LG Life Sciences official said.

LG Life Sciences said its sales rose at a faster clip after the company changed its distributor to South Korean pharmaceutical company Daewoong Co. from French drug firm Sanofi early this year.

Boryung Pharmaceutical Co., one of South Korea's largest pharmaceutical companies, expects annual sales of its high blood pressure drug Kanarb to flirt with 50 billion won this year.

In the January-September period, sales of the country's first homegrown hypertension medication stood at 33.8 billion won. "Since its launch, sales of Kanarb have been growing at a double-digit rate. For this year, the number is certain to surpass the 40 billion won mark."

After more than a decade of research and development, Boryung Pharmaceutical put Kanarb on the domestic market in 2011 and released several combination products with stronger medication effect. (Yonhap)