Is Procainamide 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 Procainamide. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Maternal doses of procainamide 2 grams daily produced low levels of the drug and its active metabolite in the milk of one mother. Although it would not be expected to cause adverse effects in older breastfed infants, the relative lack of data concerning breastfeeding during maternal procainamide therapy would argue for careful monitoring if this drug is used while breastfeeding a neonate possibly Measurement of infant serum levels could help 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. One mother was taking a dose of 500 mg 4 times daily (dosage form not stated, but probably immediate-release). Milk procainamide and N-acetyl procainamide (NAPA) levels were measured on one of the first postpartum days. Procainamide levels averaged 5.4 mg/L (range 2.6 to 10.2 mg/L), and NAPA averaged 3.5 mg/L (range 3.1 to 5 mg/L). Because the mother's serum levels were consistently below the therapeutic range, usual milk levels would probably be higher than reported here. There was no clear correlation between time after the dose and milk levels.[1] Based on data in this case, the average expected dose of procainamide plus NAPA that an infant would receive in breastmilk is less than 5% and the maximum would be less than 7% of the mother's weight-adjusted dosage.
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 Procainamide 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 “Procainamide” (LM225). 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.