The FDA issued a complete response letter to Sunovion Pharmaceuticals in regards to the new drug application for its eFlow chronic obstructive pulmonary disease drug-device combo.

The investigational eFlow closed-system nebulizer delivers a long-acting muscarinic antagonist bronchodilator, glycopyrrolate, to reduce airflow obstruction in COPD patients.

The company said it plans to work with the FDA to determine how to proceed with it’s drug-device combination product, without providing much detail as to why the FDA rejected its application.

“We are confident in SUN-101/eFlow and are committed to bringing this innovative therapy to COPD patients in the U.S. as quickly as possible,” Sunovion said in a prepared statement.

Sunovion faces competition from Theravance Biopharma, Inc. (NSDQ:TBPH) and Mylan (NSDQ:MYL), which last week touted data for its own nebulized bronchodilator in development for the treatment of COPD.

The companies’ 3-month pivotal Phase III studies enrolled more than 1,250 patients with moderate to very severe COPD.

Mylan and Theravance reported that its therapy, revefenacin, demonstrated statistically significant and clinically meaningful improvements over placebo in trough forced expiratory volume in 1 second and in overall treatment effect on trough FEV after 12 weeks of dosing.