​GlaxoSmithKline said Thursday it has received U.S. approval to sell its once-a-day respiratory inhaler Breo Ellipta for a new use in asthma patients ages 18 and older.

The expanded approval from the Food and Drug Administration will help Glaxo (NYSE: GSK) replace sales of its best-selling product, Advair, which faces generic competition in Europe and pricing pressures in the U.S.

Darrell Baker, head of the GSK Global Respiratory Franchise, noted: “Asthma is a variable condition and guidelines recommend a stepwise approach to treatment with the aim of achieving asthma control. Breo Ellipta is our second asthma treatment to be approved in the US in the past year, and now provides physicians with a range of treatment options delivered via the Ellipta inhaler to meet the needs of appropriate adult patients with differing asthma severities.”

Breo Ellipta was originally approved to treat a form of lung disease. But Thursday’s approval expands the drug’s use to a much larger patient population of roughly 19 million U.S. adults who have asthma. The inhalable formulation combines two drug ingredients that help open the lung airways: a steroid and a beta agonist.

London-based Glaxo pays royalties on Breo Ellipta to the drug’s co-developer Theravance Inc., which is based in San Francisco.

Michael Aguiar, Theravance’s CEO,. pointed out: “We believe the approval of Breo Ellipta as a once-daily ICS/LABA treatment for adults with asthma is a significant catalyst for Theravance, as asthma affects nearly 19 million adults in the US. We are pleased by today’s approval of Breo Ellipta and look forward to making this important medicine available to the appropriate adult patients among those living with the disease.”