“…Soon after, dipyrone was also identified as a cause of agranulocytosis, and cross sensitivity between dipyrone and amidopyrine was demonstrated [14]. Initially, the incidence of agranulocytosis was assumed to be the same for dipyrone as for amidopyrine [7], and the risk was suggested to be about 1 in 120 treated patients, an estimate which was based on potentially biased information from published and unpublished patient series [6,7]. However, the high magnitude of risk estimated for dipyrone has been questioned [15,16,17], and data from a large international case-control study, the International Agranulocytosis and Aplastic Anaemia (IAAA) study [15], suggest that the risk for agranulocytosis is as low as 1.1 cases per million users.…”