Mylan has announced that US regulators are going to reject its generic version of GlaxoSmithKline’s asthma/COPD inhaler Advair Diskus.

The firm revealed that it has received an update from the US Food and Drug Administration identifying “minor deficiencies” in the application that will be relayed in a Complete Response Letter later this month.

Further details on the deficiencies were not revealed.

On receipt of the official Letter, Mylan will then determine if there will be any impact on its full year 2018 outlook, it said.

This is not the first setback for the Mylan’s generic, which was rejected by the FDA last year, though it was not disclosed why the drug was deemed un-approvable at that time.

Advair Diskus (fluticasone/salmeterol) pulled in sales of around £1.61 billion in the US last year.