Endo International will spend about $8.05 billion to acquire Par Pharmaceutical as it pushes further into the generic drug market.
Endo CEO Rajiv De Silva said the deal will make Endo one of the top five generics companies as measured by U.S. sales.
Endo, based in Dublin, said it expects its generic drug unit to see double-digit revenue growth with the addition of Par.
Par, based in Woodcliff Lake, N.J., was acquired by the private equity firm TPG in 2012. The deal is expected to close in the second half of 2015.
The buyout follows Endo's failed attempt to buy Salix Pharmaceutical Ltd. after being outbid by Valeant Pharmaceutical. In March, Valeant raised its offer to about $11.11 billion, forcing Endo out of the running.
"This transaction with Par builds upon our generics growth, Endo CEO Rajiv De Silva said in a statement.
The deal includes about 18 million shares of Endo stock and $6.5 billion in cash, along with the assumption of debt.
Endo's branded products include the pain treatment Opana ER and the numbing agent Lidoderm. That unit had $285 million in revenue during the company's first quarter. The generics unit had $357 million in sales during that period.