Shire Plc is acquiring New Jersey-based rare-disease specialist NPS Pharmaceuticals, as the Irish drugmaker pursue its goal to become a biotech powerhouse via acquisitions.

Shire has agreed to pay $5.2bn (£3.4bn, €4.4bn) in cash for NPS Pharmaceuticals, which makes drugs for rare conditions.

"Shire will accelerate the growth of NPS Pharma's innovative portfolio through its market expertise in gastrointestinal (GI) disorders, core capabilities in rare disease patient management, and global footprint," the company said in a statement.

NPS is known for its two new drugs – Gattex, a treatment for short-bowel syndrome that is already on sale, and Natpara for hypoparathyroidism, which is awaiting approval from the US Food and Drug Administration.

"The acquisition of NPS Pharma is a significant step in advancing Shire's strategy to become a leading biotechnology company," said CEO Flemming Ornskov.

"With our global strength and expertise in both rare diseases and GI, Shire is uniquely positioned to drive the continued success of GATTEX/REVESTIVE, and, if approved, commercialize NPS Pharma's pipeline compound NATPARA/NATPAR."

The deal is expected to be settled in the first quarter of 2015. It would be accretive to earnings in 2016, according to Ornskov.

Shire intends to pay the consideration with an $850m bank loan, cash reserves and an existing $2.1bn revolving credit facility.

In October, Shire's $55bn deal to merge with US peer AbbVie fell apart, and it received a break-up fee of $1.6bn. AbbVie scrapped its plan to acquire Shire, after the so-called tax inversion deals faced severe criticism in the US, prompting the Obama administration to take measures to prevent such deals.

Shire is planning for further acquisitions, according to Ornskov.

"We are incredibly cash-generative and this will add to that, so this does not prevent us from considering further deals," he told Reuters.

"Shire is always considering the next deal."