Drugs giant GlaxoSmithKline has blamed the "significant impact" of cheap generic rival products in the US for a 17% fall in quarterly profits.
Cheaper rivals are winning sales
Pre-tax profits for the April to June period fell to £1.63bn ($3bn) from £1.96bn for the same period last year.
Glaxo said it was seeing the toughest trading conditions since its formation in 2000, although its results came in at the top end of expectations.
It now expects a return to profit growth in the fourth quarter of 2004.
Glaxo's US sales have been specifically hit by cheap copies of its antidepressants Paxil and Wellbutrin.
Sales of Paxil, once the group's top seller, are down 41%.
Overall Glaxo's quarterly sales fell 6% from a year ago to £5.06bn.