NEW YORK (Reuters) - Warner Chilcott, an Irish drugmaker that specializes in contraceptives and female hormone treatments, will buy Procter & Gamble Co's pharmaceuticals business for $3.1 billion, the companies said on Monday.

P&G's branded drugs, including osteoporosis treatment Actonel and Enablex for overactive bladder, have annual sales of $2.3 billion. Warner-Chilcott's annual revenue totals about $1 billion.

"The acquisition transforms Warner Chilcott into a global pharmaceutical company, expands our presence in women's health care, establishes us in the urology market in advance of the anticipated launch of our erectile dysfunction treatments, and adds gastroenterology therapies to our product portfolio," Warner Chilcott said in a release.

P&G has failed to realize its ambition of becoming a major force in pharmaceuticals, although Actonel is one of the world's top-selling treatments for prevention of fractures in post-menopausal women.

Cincinnati-based P&G, best known for its vast array of household consumer products such as Tide detergent and Crest toothpaste, said it was selling its branded medicines to "prioritize" investments in its consumer health care businesses.

The companies said the majority of the 2,300 employees in P&G's pharmaceuticals unit are expected to transfer to Warner Chilcott.

"For Warner Chilcott, the acquisition expands its presence in existing specialty pharmaceutical markets and provides access to new physician offices in 14 countries," the companies said.

Warner Chilcott said it expects the deal to close in November and be financed through borrowings.

P&G said the deal will give it a one-time after-tax gain of $1.4 billion, or 44 cents per share. But it also expects profit to be reduced by 10 cents to 12 cents per share in fiscal 2010 due to lost earnings from the pharmaceuticals business.

(Reporting by Ransdell Pierson; editing by John Wallace)