New York (AFP) - US biopharmaceutical company AbbVie said Tuesday it would buy Botox-maker Allergan for about $63 billion, moving to diversify its product line as the industry faces pressure on drug prices.

The deal, the latest large transaction in pharma, broadens the product offerings for AbbVie, which has relied heavily on sales of Humira, a drug to treat rheumatoid arthritis that faces rising competition from generics.

Combining operations would allow annual savings of at least $2 billion through trimming duplicative research and development spending and cuts in sales and marketing spending, the companies said. The deal is expected to close early in 2020.

"This is a transformational transaction for both companies and achieves unique and complementary strategic objectives," AbbVie Chief Executive Richard Gonzalez said in a statement.

"With our enhanced growth platform to fuel industry-leading growth, this strategy allows us to diversify AbbVie's business while sustaining our focus on innovative science and the advancement of our industry-leading pipeline well into the future."

Allergan, which is based in Ireland, is best known for Botox, which reduces face wrinkles. The company specializes in the areas of medical aesthetics, eye care, central nervous system and gastroenterology.

The company, which grew quickly earlier in this decade, has faced pressure from Wall Street, in part due to worries over the hit from patent expirations of eye medication Restasis. Some analysts have called for the company to be broken up.

The companies will have a combined annual revenue of $48 billion and a presence in 175 countries, the statement said.

"This acquisition creates compelling value for Allergan's stakeholders, including our customers, patients and shareholders," said Allergan Chief Executive Brent Saunders.

The offer represents a 45 percent premium over Monday's share price of Allergan, whose management recommended the operation to shareholders.

A note from Moody's affirmed Abbvie's debt rating, saying a plan to reduce debt through existing blockbusters like AbbVie's Humira and Imbruvica and Allergan's Botox is "credible."

Shares of Allergan surged 25.4 percent to $162.43, while Abbvie fell 16.3 percent to $65.70.

- Merger wave -

Abbvie has faced questions over patent expirations for Humira, which accounted for more than 60 percent of its 2018 revenues of $32.7 billion.

Allergan made more sense to buy than some smaller targets with promising drugs under development because it "meets our strategic goal to reduce reliance on Humira and allows us to continue expanding our focus on high-innovation science throughout the next decade," Abbvie said.

"Smaller bolt-on acquisitions provide opportunities for future growth but also require significant research and development investment amid scientific and clinical uncertainty," the company added.

The deal follows a variety of earlier pharma transactions, including Bristol-Myers Squibb's $74 billion takeover of Celgene announced in January.

But the Abbvie-Allergan deal must win approval from regulators. On Monday, shares of Bristol-Myers Squibb and Celgene sank after they pushed back the time-frame for closing the deal and announced plans to divest psoriasis treatment Otezla to win regulatory approval of the marriage.

A report from Moody's earlier this month predicted more mergers in the pharma industry, citing the effect of patent expirations and the 2017 US tax reform that eases the burden of companies that take on debt for acquisitions.

The report also pointed to stepped-up pressure on drug manufacturers within the health care industry on pricing, "as well as the public backlash associated with implementing large price increases."

On Monday, President Donald Trump issued an executive order that requires hospitals to disclose up front the costs of services in an easy-to-read format.