Is Metamizolo sodico Safe in Breastfeeding

I am a breastfeeding mother and i want to know if it is safe to use Metamizolo sodico? Is Metamizolo sodico safe for nursing mother and child? Does Metamizolo sodico extracts into breast milk? Does Metamizolo sodico has any long term or short term side effects on infants? Can Metamizolo sodico influence milk supply or can Metamizolo sodico decrease milk supply in lactating mothers?

Pirazolone derivative analgesic drug. Authorized and widely used drug in Europe and Latin America. Not approved in USA and UK since the 70’s because increased risk of rash, anaphylaxis and agranulocytosis (1 case out of 1 million) yet not confirmed in other settings. No untoward effects have been reported aside from a case of cyanosis in the 80’s. The American Academy of Pediatrics rates it as compatible with Breastfeeding.

Metamizolo sodico is not approved for marketing in the United States by the U.S. Food and Drug Administration or in Canada and many European countries because of its adverse reactions, including agranulocytosis. However, it is widely used in other countries during labor and breastfeeding.[1][2][3][4] After ingestion by the mother, Metamizolo sodico and its metabolites appear in breastmilk in rather large amounts. It is found in the blood and urine of breastfed infants and can cause pharmacological effects in the breastfed infant. One case of cyanotic episodes in a breastfed infant was attributed to Metamizolo sodico in breastmilk. The drug and metabolites are eliminated from the breastmilk by 48 hours after a dose and one manufacturer recommends no breastfeeding for 48 hours after a dose.[5] Safer alternatives are available for analgesia during breastfeeding.

A 42-day-old breastfed infant had 2 cyanotic episodes within 30 minutes after his mother took 3 doses of Metamizolo sodico 500 mg orally, 18, 7 and 2 hours before the first episode. A third episode occurred 24 hours after admission to the hospital. Metamizolo sodico was detected in the mother's breastmilk 24 hours after the last dose and in the infant's serum and urine. No explanation could be found for the cyanotic episodes other than Metamizolo sodico and after suspending maternal Metamizolo sodico intake, no further episodes occurred in the infant up to age 3 years. The reaction is rated as possibly caused by Metamizolo sodico in breastmilk.[6] In a blinded study, mothers who were at least 3 days postpartum and requesting analgesia for postpartum uterine pain were given either 1 gram of Metamizolo sodico or placebo. The infants of mothers who received Metamizolo sodico cried fewer times and for shorter durations in the 14 hours after drug administration than the infants of mothers who received placebo. This effect was more apparent in infants who demand fed than in those who fed on a fixed schedule.[8] Although this study appears to demonstrate a pharmacologic effect in the infants from Metamizolo sodico in milk, there is no clear explanation for the change in infant behavior. A multicenter case-control study in Brazil compared 231 children who developed leukemia before 2 years of age with 411 children with various other nonmalignant diseases. Mothers were interviewed to ascertain their analgesic use during pregnancy and lactation. Nursing mothers who took Metamizolo sodico during the three months after delivery had a 2-fold risk of having a child with acute lymphocytic leukemia and a 3.87-fold risk in having rearrangement of the MLL gene in infants under one year of age.[9]