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)/mm3.
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.