Allergan's spending spree is continuing with a deal worth nearly $2.5 billion for California, USA-based med tech group Zeltiq, in a move designed to further boost its aesthetics portfolio.

The Dublin, Ireland-based drugmaker said it has agreed to buy Zeltiq Aesthetics, which is focused on developing and commercialising products based on its proprietary controlled-cooling technology platform, for $56.50 per share, which equates to around $2.475 billion.

The firm says the acquisition will be immediately accretive with the addition of Zeltiq's flagship CoolSculpting System, which is cleared by the US Food and Drug Administration to affect appearance through lipolysis or reduction of unwanted fat using a patented cooling technology.

The system works by gently cooling targeted fat cells in the body to induce a natural, controlled elimination of fat cells without affecting surrounding tissue, serving the body contouring market the global value of which is $4 billion and growing, according to Allergan.

"By adding the best-in-class body contouring CoolSculpting System to our best-in-class facial aesthetics, plastic surgery and regenerative medicine offerings we are creating a world-class aesthetics business," said Brent Saunders, Allergan's chairman and chief executive.

"With CoolSculpting, our offerings to plastic surgeons, dermatologists and aesthetic practitioners will now extend to three of the largest and fastest-growing segments of their practices, putting Allergan in a unique position to provide expanded customer service, and help meet the needs of patients."

The deal remains subject to approval by the Zeltiq shareholders, expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, and certain other customary conditions to closing. But assuming these are obtain under standard timeframes, Allergan is expecting the transaction to close sometime in the second half of this year.

The move follows a string of deals by Allergan in 2016, including its purchase of Acelity's breast reconstruction and soft tissue repair group LifeCell in December, Chase Pharma in November, Topira Therapeutics in September, and Topokine Therapeutics back in April.