Shire, the speciality pharmaceutical company planning to shift its tax headquarters from the UK to Ireland, achieved a 14 per cent advance in first-quarter net income to $129m on the back of new sales launches.

Sales rose by a third to $703m on the back of above-market growth in its attention deficit disorder franchise, and earnings per share increased from 21.3 cents to 22.7 cents. The bulk of turnover comes from Aderall XR, its reformulated ADHD drug.

In his final results before handing over in June as chief executive to Angus Russell, the finance officer, Matt Emmens, said: “It’s been a good start to the year with sales growth from new and established products achieving our expectations.

“We are reaffirming our previous financial guidance for 2008 and continue to expect positive revenue growth through 2010.”

In spite of the surprise approval by the US Food & Drug Administration this week of Vyvanse, its once-daily adult ADHD treatment, the company held full-year sales guidance for the drug “at the lower end” of the $350m to $400m range.

The company maintained its guidance at the time of its 2007 results, with sales growth in the “mid to high teens” for 2008 and a jump in expenses, including accelerated clinical trials, marketing and depreciation.

The company said its plans to shift its tax residency from next month, while maintaining a London Stock Exchange listing, would “help protect” its tax position and “better facilitate …financial management”. The arrangement is subject to shareholder approval next month.

It said the costs associated with the change in the first quarter were $5.6m and predicted an effective tax rate on non-GAAP income at 23 per cent, an increase from 21 per cent in 2007.

Its effective tax rate for the quarter was 26 per cent, down from 27 per cent last time.

The shares closed down 4 per cent at 940p.

In a research note, UBS called the low sales estimates for Vyvanse “puzzling”, but called the overall results in line with expectations and maintained its “buy” rating on the stock.

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