Shares in Wyeth have tumbled more than 24 per cent on the New York Stock Exchange after a study that found its best-selling hormone therapy can increase a women's risk of breast cancer was abruptly halted.
The National Institutes of Health halted the three-year study after it found the risk of continued use of Prempro, a combination of oestrogen and progestin, outweigh the benefits.
Over time, Prempro increases otherwise healthy women's risk of a stroke by 41 per cent, a heart attack by 29 per cent and breast cancer by 24 per cent.
Prempro is a member of Wyeth's Premarin family of hormone replacement therapies, which generated more than £140 million of sales last year, making them the company's top selling drugs accounting for 14 per cent of revenues.
Wyeth stock dropped $11.94 a share, or 24.2 per cent, to close at $37.30 in trading yesterday on the New York Stock Exchange. The company's shares gained 20 cents in extended trading.
PA