An extensive medical review led to the conclusion that dipyrone was the most likely cause of this patient's agranulocytosis. The exact incidence, however, is hard to quantify, since only those cases that are severe enough to require a physician's care or hospitalization are actually reported. The usual presentation is that of a febrile, oropharyngeal infection. A derivative of aminopyrine, dipyrone, has also been associated with agranulocytosis. Dipyrone is currently banned in the United States, Canada, and a large number of western European countries.
Agranulocytosis is thought to be induced by dipyrone and aminopyrine via an immune reaction.
Both aminopyrine and dipyrone are metabolized to the same degradation products. One of these degradation products is a strong electrophile that can interact with the lysine side chains of the neutrophil. Subsequently, the antibody reaction induces lysis of the cells. This can occur not only in the peripheral blood but in the marrow as well. The treatment for this condition is supportive, with antibiotic therapy as indicated and withdrawal of the offending agent.