The Basics
What is Colistimethate?
Used to treat certain bacterial infections.
Brand names for Colistimethate
Coly-Mycin M
How Colistimethate is classified
Anti-Infective Agents, Antibacterial Agents, Polymyxins
Colistimethate During Pregnancy
Colistimethate pregnancy category
Category CNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Colistimethate while pregnant
Colistimethate sodium given intramuscularly during organogenesis to rabbits at 4.15 and 9.3 mg/kg resulted in talipes varus in 2.6% and 2.9% of fetuses, respectively. These doses are 0.25 and 0.55 times the maximum daily human dose based on mg/m². In addition, increased resorption occurred at 9.3 mg/kg. Colistimethate sodium was not teratogenic in rats at 4.15 or 9.3 mg/kg. These doses are 0.13 and 0.30 times the maximum daily human dose based on mg/m². There are no adequate and well-controlled studies in pregnant women. Since colistimethate sodium is transferred across the placental barrier in humans, it should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Taking Colistimethate While Breastfeeding
What are recommendations for lactation if you're taking Colistimethate?
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.
Maternal / infant drug levels
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.
Possible effects of Colistimethate on milk supply
Relevant published information was not found as of the revision date.
Possible alternatives to Colistimethate
Amikacin, Gentamicin, Imipenem and Cilastatin, Tobramycin.
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. Moiraghi A, Moiraghi P. Colistin in organic fluids. In, Herold M, Gabriel Z, eds. Antibiotics: advances in research, production and clinical use; proceedings of the Congress on Antibiotics held in Prague, 15-19 June, 1964. London. Butterworths. 1966;188-92.
2. Borderon E, Soutoul JH et al. [Excretion of antibiotics in human milk]. Med Mal Infect. 1975;5:373-6.
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
