Is Quinidine safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Quinidine. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Limited information indicates that maternal doses of quinidine up to 1.8 grams daily produce low levels in milk and would not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months. Exclusively breastfed infants should be carefully monitored if this drug is used during lactation, possibly including measurement of serum levels to rule out toxicity if there is a concern.
Effects on the breastfed infant
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. In one case report, a quinidine milk level of 6.4 mg/L was reported 3 hours after a dose while taking 600 mg every 8 hours orally of a sustained-release quinidine sulfate preparation (Quninidex). In the same patient, a random milk level of 8.2 mg/L was also measured.[1] Data from this case indicate that a breastfed infant would receive about 3 to 4% of the maternal weight-adjusted dosage of quinidine.
Infant Levels. Relevant published information was not found as of the revision date.
“No published information” means the studies do not exist yet — not that Quinidine is known to be harmful, and not that it is known to be safe. Your prescriber or pharmacist can weigh your baby's age and whether a better-studied alternative would do the same job. Worth asking before stopping a medicine you need.
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Quinidine” (LM235). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.