(Reuters) – Mylan NV said on Wednesday that U.S. health regulators were unable to approve its generic version of GlaxoSmithKline’s blockbuster inhaled lung drug Advair, citing “minor deficiencies” with the drug.
Shares of Mylan fell 4.3 percent to $39.90 after the bell.
Mylan did not provide details on the nature of the deficiencies cited by the FDA and it remains unclear whether the company will be able to resolve them and snag an approval this year.
The U.S. Food And Drug Administration has declined several Advair knock-offs in the past from drugmakers including Novartis AG, Hikma Pharmaceuticals and Mylan itself, whose generic was rejected last year.
The news comes as unexpectedly good news for GSK, which reported revenue of 3,130 million pounds ($4.19 billion) from Advair last year, and has been bracing for competition at least by mid-2018.
Mylan said here it expects to receive a formal complete response letter, typically issued to outline concerns and conditions that must be addressed to gain U.S. approval, from the FDA on June 27 and would determine what impact, if any, it would have on its full-year forecast.
Reporting by Tamara Mathias in Bengaluru; Editing by Maju Samuel