gms | German Medical Science

Background: The use of metamizole (dipyrone) increases in many countries, although there is still a controversy on its safety because it can cause agranulocytosis. Aim of this study was to analyse spontaneous reports of agranulocytosis attributed to metamizole with regard to patient and treatment characteristics as well as outcomes and compare these findings between countries.

Materials and methods: Reports of suspected metamizole-associated agranulocytosis to the EudraVigilance database were assessed up to 2017. Based on these data, demographic variables (age, sex and country of reporting) and other information such as indications for metamizole, dosing, duration of use, comorbidities and outcomes were used.

Results: A total of 1,448 reports from 31 different countries were included (Germany 42.0%; Spain 29.6%; Switzerland 13.1%; other countries 15.3%). Mean age of patients was 53.6 years (63.4% females). Oral use was least often found in Spain (67.3%) and most often reported in Switzerland (93.9%). Median time between starting metamizole and developing an agranulocytosis was 13 days with 34.7% of cases occurring up to 7 days. This time was much shorter in patients who had already received metamizole before (median: 6 vs. 15 days). About 16% of cases ended fatal. In fatal cases, patients were older and previous use of metamizole was more frequent (13.3% vs. 8.5%).

Conclusion: Metamizole-associated agranulocytosis is still a life-threatening condition. As it can develop weeks after last administration and independently of dose and duration of treatment prescribers and patients should be aware of its signs and symptoms to be able to intervene as soon as possible.