Oct 21 (Reuters) - The U.S. Food and Drug Administration on Wednesday declined to approve Qtrypta, Zosano Pharma Corp's experimental treatment to relieve pain after the onset of migraine headaches, citing issues with the drug delivery during clinical trials.

The decision comes after the agency in September raised similar concerns with the company's marketing application for the treatment. (Reporting by Amruta Khandekar and Manojna Maddipatla in Bengaluru; Editing by Shailesh Kuber)