Is Colistimethate 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 Colistimethate. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Limited data indicate that colistin is minimally excreted into breastmilk following intramuscular administration of colistimethate. Because colistin is poorly absorbed orally, it is unlikely to be absorbed in appreciable amounts by the infant or adversely affect the breastfed infant. However, no studies have evaluated serum levels or adverse effects in breastfed infants whose mothers were receiving colistimethate. Breastfeeding is acceptable with the use of inhaled colistin or colistimethate.[1]
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. A single dose of colistimethate equal to 33 mg of colistin was given intramuscularly to 9 women and milk levels were measured once in each woman over the next 3 hours. Milk concentrations were 740 mcg/L at 1 hour (n = 1), 760 mcg/L at 2 hours (n = 3) and 140 mcg/L at 3 hours (n = 5) after the dose. Another 20 women were given single intramuscular doses equivalent to 66 mg of colistin. Milk concentrations averaged 500 mcg/L (range 160 to 1100 mcg/L) at 1 hour after the dose, and 789 mcg/L at 2 hours after the dose (range 0 to 2100 mcg/L).[2]
Colistimethate was given to 15 women intramuscularly on day 5 postpartum in a dose equivalent to 66 mg of colistin. After 2 doses, the average peak level was 165 mcg/L and trough was 50 mcg/L. Another 5 women were given a dose equivalent to 132 mg of colistin intramuscularly on day 5 postpartum. After 2 doses, the average peak level was 215 mcg/L and trough was 50 mcg/L. With both doses, peak milk levels occurred 5 hours after the dose.[3]
Infant Levels. Relevant published information was not found as of the revision date.
Alternatives LactMed lists
“No published information” means the studies do not exist yet — not that Colistimethate 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 “Colistimethate” (LM453). 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.