Analgesic Use, Agranulocytosis, and Aplastic Anemia

To the Editor.— The International Agranulocytosis and Aplastic Anemia Study 1 is of special concern wherever the analgesic antipyretic drug dipyrone continues to be sold. There are important reasons, however, for reserving judgment as to whether this multicenter case-control study could predict the risks of dipyrone-induced agranulocytosis. In particular, there is no mention of how soon blood sampling was performed for detection and confirmation of agranulocytosis after the appearance of symptoms. Agranulocytosis associated with dipyrone use (reviewed by de Gruchy 2 ) develops acutely (within hours), is self-limiting, and probably involves peripheral destruction of neutrophils in previously sensitized patients. After stopping treatment with the offending drug, recovery of the white blood cell count to normal values may become evident within 24 to 48 hours. 3 Patients can nevertheless be rendered very ill and even die. At a meeting in Indonesia, it was revealed that the patients in this study from whom