Botox maker Allergan (AGN) agreed this week to buy MAP Pharmaceuticals (MAPP) for just under $1.0 billion in cash as it looks to expand its reach in the neuroscience health market.

The two in January 2011 agreed to jointly sell the migraine drug Levadex, which was developed by MAP Pharmaceuticals and is awaiting approval from the U.S. Food and Drug Administration.

The cash deal, which is valued at $958 million, or $25 a share, represents a 60% premium to MAP’s closing price on Tuesday. 

Irvine, Calif.-based Allergan has been expanding its presence in the migraine market, having received regulatory approvals in 56 countries over the last few years for Botox as a treatment of chronic migraine.

“We plan to capitalize on this depth of expertise in Neurology as we continue the global development of Levadex as a potential acute treatment for migraine,” said Allergan CEO David Pyott.

Shares of MAP on Wednesday soared nearly 59%, while those of Allergen were virtually flat.

Assuming the transaction closes as planned and Levadex approval comes by the formerly established date of April 15, Allergan said the transaction will be dilutive to its fiscal 2013 earnings by approximately 7 cents, but accretive in the second half of 2014.

Excluding the special acquisition costs, Allergan said it anticipates current EPS growth expectations to fall within its mid-teens growth aspiration.

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