Correction

In our article on makers of branded and generic drugs (“Protection racket”, May 19th), we said that the American patent on one of Aventis's best-selling heart drugs expired in 1998; in fact it will expire in 2011. We also said that the Federal Trade Commission had concluded that the arrangement between Aventis and Andrx had blocked market entry of competitors. The FTC actually concluded that the arrangement had not blocked new entrants, although it has moved to bar such arrangements in future because of their potential to do so. We apologise for these errors.