Pharmaceutical firm Shire posted a 20% rise in first-quarter earnings on Thursday, just beating market expectations, as its drugs to treat hyperactivity again lifted market share in the United States.

Shire, whose growth has outstripped the industry thanks to its acquisitive strategy, reported earnings per ADS (American Depositary Share) of $1.48 in the three months to end-March, on revenue 21 % higher at $1.17 billion.

Chief Executive Angus Russell said Shire performed strongly in the quarter, with its ADHD (attention deficit hyperactivity disorder) drugs Vyvanse and Intuniv both increasing share in a growing U.S. market.

Vyvanse had sales of $260 million in the quarter, up 29% and putting it on track to exceed $1 billion this year.

Shire, which wants to extend the stimulant into new areas, also announced positive results from a study into its use to treat binge eating disorder.

The group said for the full year it now expected product sales growth in the mid teens, from its earlier forecast of low to mid teens, and revenue growth in the low teens.

Analysts at Deutsche Bank said it was a strong quarter, with growth in both ADHD, up 24%, and human genetic therapies, up 29%, remaining strongly in double digits.

"For a change, the upside versus consensus did not come from old ADHD drug Adderall XR but from its newer follow-on Vyvanse," they said.

Performance defence

Shire was a pioneer in buying drugs in the later stages of development rather than identifying candidates from its own early-stage research.

Its big pharma rivals, many of which have had a disappointing return from R&D, are adopting a similar strategy, triggering a wave of M&A in the sector and increasing speculation that Shire will be a target itself.

Russell declined to comment on market rumours but he said the group was prepared for any event, although it had no special defences, which would be unpopular with shareholders.

"The best bid defence at the moment is our outstanding performance and our high PE (price-earnings) ratings," he said.

Shires itself bought U.S. biotech firm FerroKin BioSciences, which develops treatments for patients with iron overload, for up to $325 million last month. It followed this up by snapping up assets from vascular technology firm Pervasis Therapeutics.

But the group also had a couple of setbacks, including the failure of a clinical study for a new use of its bowel drug Lialda, and the pulling of its application for rare disease drug Replagal in the United States.

The withdrawal of Replagal, a treatment for Fabry disease, which it was supplying free to patients because of a shortfall in supplies from Sanofi-owned rival Genzyme, came when the U.S. regulator said it needed more tests.

Analysts expected Shire to post revenue of $1.15 billion and non-GAAP earnings per ADS of $1.46, according to a company-compiled consensus of 16 brokers.