* Q4 earnings up 17 pct, just shy of expectation
* Revenue up 19 pct, in line with forecasts
* Sees mid-single digit earnings growth this year
* Shares up 2.6 pct (Adds CEO comments, analyst reaction, shares)
By Paul Sandle
LONDON, Feb 12 (Reuters) - Shire, the drugs company buying rare disease specialist NPS Pharma, said 2015 had got off to a flying start, marked by its biggest acquisition to date and the approval of the first drug to treat binge-eating disorder.
The Dublin-based firm, which is spending $5.2 billion on NPS, said on Thursday profit would grow by a mid-single digit percentage this year, after it posted earnings per share of $2.63, just short of market forecasts, for the fourth quarter of 2014.
Chief Executive Flemming Ornskov said following an "exceptional 2014", he expected further growth in 2015, despite the loss of exclusivity on hyperactivity drug Intuniv and currency headwinds.
"We have excellent momentum and we are gaining even further momentum," he told reporters.
Revenue at the group, which has franchises in medicines for hyperactivity and rare genetic diseases, rose 19 percent to $1.58 billion, beating forecasts for $1.55 billion.
Shares in Shire, which was set to be bought by AbbVie last year for 5,248 pence a share, were trading up 2.6 percent at 4,899 pence by 1345 GMT. The U.S. group pulled the plug on the $55 billion deal after changes to U.S. tax rules.
Analyst Mick Cooper at Edison said the results showed why Shire remained such an attractive asset for potential suitors.
The group said it expected lower product sales growth -- in the low-to-mid single digits -- this year after the loss of patent protection on Intuniv in December 2014, and the impact of the strong dollar, particularly on its rare disease drugs in Europe.
Earnings growth would be in the mid-single digits in 2015, it said. The forecast includes the contribution from NPS.
Analysts at Jefferies said the fourth-quarter numbers were largely as expected, although earnings per share were 2 percent shy on greater finance costs and higher tax.
"Importantly the initial 2015 outlook is broadly similar to our estimates, with margin fears into the quarter likely overdone," they said.
Shire swooped on NPS last month just weeks before the U.S. Food and Drug Administration ruled on its drug Natpara for hypoparathyriodism. The gamble paid off when Natpara, which could generate annual sales of $542 million, was approved.
The U.S. regulator had more positive news this month when it approved Shire's big-selling hyperactivity drug Vyvanse for binge eating, making the stimulant the first product given the go-ahead for a condition that affects an estimated 2.8 million people in the United States. (Editing by Sarah Young and Mark Potter)