SHARES in Shire Pharmaceuticals, the troubled blue-chip drugs group, yesterday plunged 7 per cent to 293p after the company admitted that it had failed to find a new chief executive.

Rolf Stahel, the chief executive, resigned in the autumn after a boardroom split.

Yesterday the company said that it had drawn up a shortlist of three candidates and insisted that it was on target to make an announcement within the next three months.

But the shares still plummeted, depressed further by news of further delays for the approval of Forsenol, a kidney disease drug.

The news took the shine off the group’s full-year profits which were in line with City expectations.

Robin Gilbert, an analyst at Numis Securities, said “It is not a logical share price drop but this market punishes any company uncertainties.”

The group said that a European regulator had asked for additional information about Forsenol before granting approval.

It added that approval would not now be expected to come through until the second half of the year.

However, Shire said that approval from the US Food and Drugs Administration was expected as early as today and that out of six new products awaiting regulatory approval five were on track.

Another analyst said that he was surprised at the slide in Shire’s shares, having quelled fears that it would lose sales in its key hyperactivity treatment market to a new rival.

Shire said it had maintained market share despite the fast growth of Strattera, a rival treatment to its Adderall drug launched by Eli Lilly, the US pharmaceutical group, in January. Shire also bought the worldwide sales and marketing rights to Methypatch, a new treatment for Attention Deficit and Hyperactivity Disorder (ADHD) that is delivered to the patient through a skin patch.

Analysts said that Methypatch would give Shire access to a new market, as it was based on methylphenidate, which accounts for 53 per cent of the ADHD treatment market and is a rival to Shire’s existing Adderall products. Shire expects to launch the patch, which is awaiting approval by the US Food and Drugs Administration, in the second half of next year.

In the 12 months to December 31, pre-tax profit before exceptionals rose to $329.1 million (£208 million), up from $101.5 million the previous year.

Revenue climbed to $1.06 billion from $877.6 million.