Both companies' boards unanimously approved the deal, which is expected to close late in the first quarter or in the second quarter.
Allergan expects to fund the acquisition with available cash, cash equivalents and short-term borrowings under its commercial paper program. The transaction is not subject to any financing contingency.
Allergan Inc. anticipates the buyout hurting its 2013 earnings by about 7 cents per share and adding to its earnings per share by 2014's second half. The Irvine, Calif. company said it will give its 2013 outlook on Feb. 5.