Patents on many of the world's best-selling medicines expire over the next several years, opening a large market to generic and biosimilar entrants. Industry estimates put its scale at roughly 900 trillion won.

Once a patent lapses, other companies may make the same compound. Chemically synthesized copies are generics; copies of biologics such as antibodies are biosimilars. Because the latter cannot be replicated exactly, they require separate comparative clinical work.

How far do prices fall

Generics settle well below the originator's price once several competitors enter. Biosimilars, with higher development and manufacturing costs, fall less — but still enough to matter greatly for patients and insurance budgets.

Insurance authorities treat these windows as an opportunity to cut drug spending. Korea operates a system for adjusting reimbursement ceilings on off-patent medicines.

Where Korean companies stand

Korea has built a substantial position in contract manufacturing of biologics and in biosimilar development. With large-capacity plants winning global orders, the expiry wave could bring more work.

But crowded competition pulls prices down as well. Volume up, margins down has been the recurring pattern, and most in the market expect the same pressure this time.