Metamizole Use by Latino Immigrants: A Common and Potentially Harmful Home Remedy Joshua L. Bonkowsky, MD, PhD*; J. Kimble Frazer, MD, PhD*; Karen F. Buchi, MD*‡; and Carrie L. Byington, MD*‡§ ABSTRACT. A 4-year-old boy presented with fever, septic arthritis, and persistent neutropenia. Bone marrow biopsy revealed no evidence of neoplasia. Additional history disclosed that the patient had been given met- amizole for pain before onset of his illness. Metamizole, a nonsteroidal antiinflammatory agent, is prohibited in the United States because of the risk of agranulocytosis but is widely used in Mexico and other countries. The increasing number of Latinos in the United States and the extensive cross-border transfer of medicines raise concerns that metamizole use and associated complica- tions may become more frequent. After identification of the index patient, additional inquiry revealed that the patient’s mother was hospitalized previously for over- whelming sepsis associated with metamizole use. These cases prompted an investigation of metamizole use in an urban pediatric clinic, which revealed that 35% of Span- ish-speaking Latino families had used metamizole; 25% of these families had purchased the medication in the United States. We conclude that metamizole use is com- mon and may be underrecognized in immigrant Latino patients. Physicians in the United States, especially those who practice primary care, hematology/oncology, and in- fectious diseases, must be aware of the availability and use of metamizole in specific patient populations and its potential for harmful side effects. Pediatrics 2002;109(6). URL: http://www.pediatrics.org/cgi/content/full/109/6/ e98; metamizole, neutropenia, home remedy. ABBREVIATIONS. WBC, white blood cell; ANC, absolute neutro- phil count; G-CSF, granulocyte-colony stimulating factor. M etamizole, or dipyrone, is a pyrazolone nonsteroidal antiinflammatory agent. 1 It has been associated with fatal agranulocy- tosis and was withdrawn from the US market by the US Food and Drug Administration in 1979. 1 Met- amizole is available without a prescription in Mexico and other countries and is used to treat fever and pain. It is marketed in Latin America under hun- dreds of brand names, including Neo-melubrina (Ta- ble 1). Despite the common use of metamizole in other countries and warnings issued in the United States to travelers regarding the risks of medications that contain pyrazolone analgesics, 2 many US physi- cians remain unaware of these potentially harmful medications. CASE REPORTS A 4-year-old Latino boy presented to an urban public health clinic in Salt Lake City, Utah, for evaluation of limp and fever. His parents had given him Neo-melubrina (metamizole) for his symp- toms. His medical history was unremarkable. The boy’s family history was remarkable for sepsis in the mother 5 months before the child’s illness. His social history was notable for recent emi- gration from Mexico. Physical examination revealed a temperature of 39.5°C and active resistance to rotation of his left hip. Laboratory testing demonstrated a white blood cell count (WBC) of 3800/L (19% band forms, 26% segmented neutrophils, 48% lymphocytes, 7% monocytes), absolute neutrophil count (ANC) of 1710, hemoglobin 12.3 g/dL, platelets 285 000/L, Westergren erythrocyte sedimen- tation rate of 20 mm/h, and C-reactive protein of 1.7 mg/dL. Radiographs of the hips showed an effusion on the left, subse- quently confirmed by ultrasonography. A bone scan was normal. Hip joint aspiration yielded cloudy fluid; Gram stain was nega- tive. A bacterial culture of synovial fluid was obtained. The patient was admitted, and treatment with nafcillin and clindamycin was initiated. The patient remained febrile to 40.4°C, and the C-reactive pro- tein increased to 4 mg/dL. The WBC decreased to 2800/L with an ANC of 1190. Hematopathologic evaluation of the peripheral blood smear revealed neutropenia, lymphopenia, and a single myeloid blast. The synovial fluid culture yielded Enterobacter ag- glomerans. Antibiotic coverage was adjusted. Left hip arthrotomy and bone marrow biopsy were performed 2 days after admission. The bone marrow demonstrated normocellular marrow and no evidence of myelodysplasia but revealed myeloblastosis consis- tent with a reactive process. The patient’s ANC decreased to 640. The patient received 2 doses of granulocyte colony-stimulating factor (G-CSF) with temporary improvement. A repeat bone mar- row biopsy was performed 22 days after admission secondary to a persistently low ANC; no evidence of a neoproliferative process was seen. The patient completed a 28-day course of antibiotics. One month postdischarge, his WBC was 5500/L with an ANC of 3410. The patient’s 27-year-old mother was interviewed, and her medical records were reviewed. She reported 1 week of fever and abdominal pain 5 months before her child’s presentation for which she purchased Neo-melubrina and an antibiotic to treat her symp- toms. Her symptoms worsened, and she was admitted to the hospital with a temperature of 40°C, disseminated intravascular coagulation, and shock. Computed tomography of the abdomen revealed acute cholecystitis. She required treatment in the inten- sive care unit, and she completed a 10-day course of antibiotics. During her hospitalization, her WBC counts ranged from 3000 to 4000/L with an ANC of 1500 to 2000 and an absolute lymphocyte count of 700. The family purchased Neo-melubrina without a prescription from a Latin American market in Salt Lake City. No directions or warnings were included with the medication. Members of the clinic staff were able to purchase the same medication at the market. From the *Department of Pediatrics, ‡Division of General Pediatrics, §Di- vision of Infectious Diseases and Geographic Medicine, University of Utah, Salt Lake City, Utah. Received for publication Dec 28, 2001; accepted Feb 14, 2002. Reprint requests to (C.L.B.) Division of Infectious Diseases and Geographic Medicine, Department of Pediatrics, University of Utah, 50 North Medical Dr, Salt Lake City, UT 84132. E-mail: cbyington@med.utah.edu PEDIATRICS (ISSN 0031 4005). Copyright © 2002 by the American Acad- emy of Pediatrics. http://www.pediatrics.org/cgi/content/full/109/6/e98 PEDIATRICS Vol. 109 No. 6 June 2002 1 of 3 by guest on November 8, 2016 Downloaded from