Federal regulators said the safety of an experimental lung drug from GlaxoSmithKline PLC received a better-than-expected initial review as a method of treating chronic obstructive pulmonary disease, or COPD.

The U.S. Food and Drug Administration will review the drug Breo Ellipta on Wednesday, which was made by GlaxoSmithKline PLC and its partner Theravance Inc. Breo is designed to be dosed once daily and has the potential to be a successor to Glaxo's Advair, which should be taken twice daily. The company said a once-daily product should boost the number of people who remember to use the COPD medicine, which has the potential to improve overall disease management and cut health costs.

COPD is a condition that includes emphysema, chronic bronchitis or both. COPD is the third leading cause of death in the United States, according to federal data.

According to FDA's website, initial reviews of the drug says its overall safety was consistent with similar drugs, which came as a relief to investors who were concerned that the agency might dwell on an increase in the number of cases of pneumonia in patients treated with Breo.

The FDA's safety review looked at lung-infection risks like pneumonia. An increased risk of pneumonia has been associated with other inhaled corticosteroids for COPD, according to FDA.

The evidence to support the benefit of the combination over vilanterol alone to relax the airways "are less robust," FDA staff said. The combination performed better reducing exacerbations of the disease.

 The drug may generate $1.3 billion in sales for London- based Glaxo in 2018, according to the average of five analysts' estimates compiled by Bloomberg. Theravance will receive royalties of 15 percent on the first $3 billion of sales and 5 percent on any sales higher, said Rick Winningham, chief executive officer of South San Francisco, California-based Theravance, according to Bloomberg.