(Adds company comment from conference call, analyst comment; updates share movement)
By Bill Berkrot
June 30 (Reuters) - Allergan Inc said on Monday that the U.S. Food and Drug Administration would not approve its acute migraine aerosol treatment until certain concerns are addressed, but the agency approved a new use for its implantable eye drug, Ozurdex.
The Botox maker, which is fighting a hostile takeover bid by Valeant Pharmaceuticals International Inc, said Semprana, formerly known as Levadex, had received a second "complete response letter" from the FDA delaying its approval. Allergan now expects the agency's next action in the second quarter of 2015.
Allergan shares were down 2.4 percent at $169.81.
In its letter, the FDA expressed concern about the delivery device for the aerosol migraine medication, citing "content uniformity on the improved canister filling process and on standards for device actuation," Allergan said.
"We believe we may have existing data to answer FDA's questions," Allergan research and development chief Scott Whitcup told analysts on a conference call on its pipeline of drugs in development.
"There is no scenario I can imagine under which we would not take this forward," Whitcup said.
JPMorgan analyst Chris Schott called the Semprana delay a modest negative, but added in a research note: "We expect the company to respond to the FDA by year end and now believe we could see an approval by the second quarter of 2015."
Allergan also announced plans to begin large Phase III trials of its closely watched Darpin treatment for wet age-related macular degeneration in the second quarter of 2015.
The company has cited the future sales potential of Darpin and Valeant's lack of commitment to research and development as one of its arguments for remaining independent.
"Valeant has neither the expertise nor the commitment to maximize the value of Darpin," Allergan said in its pipeline presentation on Monday.
Data from a small Phase II trial appears to suggest that Darpin is at least as effective as Roche's Lucentis, with a longer duration of activity.
Allergan said it believed Darpin could dry the retina more quickly and effectively than current treatments, possibly leading to superior vision improvement. The drug would also compete with Regeneron Pharmaceutical Inc's Eylea.
Allergan said an improved manufacturing process could reduce incidence of ocular inflammation seen in earlier Darpin trials.
But JPMorgan's Schott said: "Today's update does not change our view that a potential combination with Valeant represents the path to greatest value creation for both companies."
Ozurdex, Allergan's sustained-release biodegradable steroid implant, received additional U.S. approval to treat diabetic macular edema (DME) in adult patients who have an artificial lens implant or are scheduled for cataract surgery.
Allergan said it hoped to receive European DME approval in the second half of this year.
The drug was previously approved to treat macular edema and non-infectious ocular inflammation. (Additional reporting by Caroline Humer; Editing by Lisa Von Ahn)