Johnson & Johnson is buying blood pressure specialist Actelion in an all-cash deal that values the company at $30bn (£23.8bn), following months of complex negotiation and marking the first big pharmaceuticals transaction of the year.

J&J, a US drugs and consumer goods giant, will use its cash reserves stored overseas to pay $280 a share for Actelion, reflecting a 23pc premium to the Swiss company's share price before news of the acquisition broke.

The deal will give J&J ownership of Actelion's top-selling drug, Tracleer, in addition to others that are already on the market. It will not only feed J&J's pipeline but give it exposure to a new therapy area and immediately boost the company's profits.

The acquisition is not, however, a straightforward M&A deal. Immediately before it completes, Actelion will spin out its research and development into a new, billion-pound publicly listed Swiss company called R&D NewCo, of which J&J will hold a 16pc stake, with the right to acquire more.

Mintoi Chessa-Florea, global head of healthcare coverage at Mergermarket, called the transaction another example of creative deal-making in big pharma.

"​In recent years we have seen the sector forge multi-billion joint ventures, asset swaps and spin-offs so that an Actelion takeover cum-spin-off is yet another melange of such precedents," she said.

"The Swiss biotech’s longstanding commitment to research and independence and J&J’s desire to become a market leader in the pulmonary arterial hypertension, means both parties can benefit."