Metamizole Related Granulocytopenia and Agranulocytosis: An Analysis of 13 Children

Abstract

Abstract Objectives: Metamizole sodium (Novalgin ® ) is an effective, widely used analgesic and antipyretic agent in several countries. In spite of its availability and common usage, it has serious and potentially fatal adverse effects like agranulocytosis and aplastic anemia. Objectives of this study are to evaluate incidence, severity, and clinical significance of metamizole related neutropenia and agranulocytosis, and to study recovery duration of neutropenia and agranulocytosis in children exposed to metamizole. Material and Methods: Thirteen cases of neutropenia and/or agranulocytosis secondary to metamizole usage have been evaluated retrospectively. Duration and cumulative doses of metamizole, degree of neutropenia, recovery from neutropenia, and other complications related to neutropenia were evaluated. Results: Overall, thirteen granulocytopenic patients were recorded for 12 months after metamizol usage. Mean metamizole exposure duration was 4,64 (2-7) days; mean daily total metamizole dose was 40 (15,6-78) mg/kg; mean metamizole cumulative dose was 219,4 (58,8-468) mg/kg; mean neutropenia duration was 9,4 (1-30) days; and mean absolute neutrophil count was 690 (30-1300)/mm 3 . Four patients who used ≥ 30 mg/kg daily doses of metamizole for 4-7 days (≥ 217 mg/kg cumulative dose) had agranulocytosis. All of the patients recovered fully after metamizol cessasion. The shortest recorded recovery duration from granulocytopenia was 2 days while the longest recorded recovery duration was 30 days. Conclusion: Physicians should be aware of the toxic effects of metamizole and should not prefer metamizole as a first line antipyretic agent. Neutropenia and agranulocytosis risks should be kept in mind in the application of metamizole particularly over long periods of time and in large doses in children. Key Words: Metamizole; Granulocytopenia; Agranulocytosis; Childhood.