(Reuters) - Theravance Biopharma Inc and partner Mylan NV on Friday won U.S. regulatory approval for their treatment for a chronic lung condition that causes breathing-related problems.

The treatment, Yupelri here, is a once-daily inhalable solution to be used by patients of chronic obstructive pulmonary disease (COPD), a lung disease characterized by wheezing or chronic cough.

Yupelri belongs to a class of drugs called long-acting muscarinic antagonists (LAMA), with the existing treatment options primarily being hand-held devices such as Boehringer Ingelheim’s Spiriva.

The treatment is expected to be made available in the United States before the end of the year, Theravance and Mylan said in a statement.

About 9-10 percent of COPD patients in the United States prefer a nebulized product for maintenance therapy, Raymond James analyst Elliot Wilbur said in a note prior to the approval.

Baird Equity Research analyst Brian Skorney, who forecasts peak sales of more than $250 million for Yupelri in 2030, expects a tough launch for the treatment as the COPD market becomes increasingly complicated with branded and generic options.

“We think the opportunity for a nebulized LAMA is relatively limited by the treatment paradigm in COPD, where combination therapy is the mainstay and there is wide availability of numerous inhalers containing two-three mechanisms in one,” Skorney said in a note.

Sunovion Pharmaceuticals Inc's Lonhala Magnair, the only other nebulized LAMA treatment, was approved here by the FDA late last year.

COPD is a collective term for a group of lung diseases commonly triggered by long-term smoking and exposure to air pollutants. The World Health Organization predicts COPD to become the third leading cause of death worldwide by 2030.

Mylan’s shares closed marginally down at $36.95 on Friday, while Theravance ended up 5.1 percent at $25.81.