Is Procainamide safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Procainamide. This is a summary of that source — not our own verdict.
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: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.