Shares in Irish biopharma group Amarin fell sharply today after it announced plans for a sale of 21.7 million new shares in an underwritten public offering.

The company said it would sell the American Depositary Shares at market prices and use the proceeds to continue the commercial launch of Vascepa, its pharmaceutical grade purified fish oil for the treatment of patients with very high blood fats, or triglycerides. The company, which already has just over 150 million shares in issue, saw its stock price tumble 8.4 per cent to $5.65 when the Nasdaq opened today.Amarin started selling Vascepa in the United States in January.

The company said it had sold 18,367 prescriptions of Vascepa in June, up from 16,076 in May, and 3,224 in February, the first full month on the market.