IRVINE, Calif. (AP) — Allergan Inc. said today that the Food and Drug Administration isn’t ready to approve its inhaled migraine treatment Levadex

Allergan said the FDA is concerned about elements of the manufacturing process for Levadex. The company said it is already responding to those concerns because the FDA had identified them in previous discussions. In March 2012, the FDA said it could not approve Levadex until the concerns related to manufacturing and other issues were addressed.

Allergan has since bought a company that was involved in the manufacturing process, and it also plans to make some minor changes to the product label.

The company is working to address all of the FDA’s concerns and said the agency will next take action by year-end.

Allergan said the FDA’s decision does not affect its annual revenue guidance because it had only expected minimal sales of Levadex this year even if it had been approved on time.

Levadex is intended to treat migraine headaches in adults. Allergan acquired the drug candidate in March when it bought MAP Pharmaceuticals for $958 million. The companies had agreed to collaborate on the drug in 2011. Allergan makes Botox, which is most famously used for removing wrinkles on the forehead, but is also approved to treat migraines and other conditions. The company said it hopes to use Levadex as a complementary treatment for migraines.

Shares of Allergan lost 89 cents to $113.14 in morning trading.