On 1 September we published a drug point about hypersensitivity reaction to balsalazide by V Adhiyaman and colleagues (p 489). The authors and other readers have pointed out to us that we published the same piece on 4 March last year. We have tried to find out how this might have happened, but because of the time lapse our investigation has been fruitless. We apologise for this production error, and we reassure readers that we are examining our procedures to ensure that such duplication does not recur.
. 2001 Oct 20;323(7318):900.