Shares in Amarin, the drug development company run by former Elan executives, plunged yesterday after trials of its Huntington's disease drug failed to improve the condition of patients.

Almost €200 million was wiped off the value of the company as the shares dived almost 80 per cent on Irish, UK and US markets. In Dublin and London, where the shares traded on the IEX and AIM, the stock closed down 77 per cent and 75 per cent respectively, at 64 cent and 47 pence. On the Nasdaq the shares were down 80 per cent, to 76 cent.

Although the shares trade mainly outside Ireland, dealers in Dublin said several Irish people would be nursing substantial losses, including Amarin chairman and former Elan finance director Tom Lynch, who owns 18 per cent of Amarin.

In a statement to the stock exchange, Amarin said the results of two phase-three trials of Miraxion had shown no statistically significant difference between the condition of those taking the drug and those who took a placebo.

"We are extremely surprised and disappointed by these top-line results," said Amarin chief executive Rick Stewart. He said the findings were inconsistent with earlier trial data, which had shown a statistically significant difference in a subset of patients with Huntington's disease.

Mr Stewart said the company would continue to examine the trial data to better understand the outcome. "We are particularly disappointed that, at this time, we are not in a position to bring any positive news to those patients who are suffering from this devastating disease," he said.