Risk Factor: D
Class: Anti-infectives/ Aminoglycosides
Fetal Risk Summary
Kanamycin is an aminoglycoside antibiotic. At term, the drug was detectable in cord serum 15 minutes after a 500-mg IM maternal dose (1). Mean cord serum levels at 36 hours were 6 g/mL. Amniotic fluid levels were undetectable during the first hour, then rose during the next 6 hours to a mean value of 5.5 g/mL. No effects on the infants were mentioned.
Eighth cranial nerve damage has been reported following in utero exposure to kanamycin (2,3). In a retrospective survey of 391 mothers who had received kanamycin, 50 mg/kg, for prolonged periods during pregnancy, 9 (2.3%) children were found to have hearing loss (2). Complete hearing loss in a mother and her infant was reported after the mother had been treated during pregnancy with kanamycin, 1 g/day IM for 4.5 days (3). Ethacrynic acid, an ototoxic diuretic, was also given to the mother during pregnancy.
Except for ototoxicity, no reports of congenital defects due to kanamycin have been located. Embryos were examined from five patients who aborted during the 11th12th week of pregnancy and who had been treated with kanamycin during the 6th and 8th weeks (2). No abnormalities in the embryos were found.
Breast Feeding Summary
Kanamycin is excreted in breast milk. Milk:plasma ratios of 0.050.40 have been reported (4). A 1-g IM dose produced peak milk levels of 18.4 g/mL (5). No effects were reported in the nursing infants. Because oral absorption of kanamycin is poor, ototoxicity would not be expected. However, three potential problems exist for the nursing infant: modification of bowel flora, direct effects on the infant, and interference with the interpretation of culture results if a fever workup is required. The American Academy of Pediatrics considers kanamycin to be compatible with breast feeding (6).
- Good R, Johnson G. The placental transfer of kanamycin during late pregnancy. Obstet Gynecol 1971;38:602.
- Nishimura H, Tanimura T. Clinical Aspects of The Teratogenicity of Drugs. New York, NY:American Elsevier, 1976:131.
- Jones HC. Intrauterine ototoxicity. A case report and review of literature. J Natl Med Assoc 1973;65:2013.
- Wilson JT. Milk/plasma ratios and contraindicated drugs. In Wilson JT, ed. Drugs in Breast Milk. Balgowlah, Australia:ADIS Press, 1981:79.
- O’Brien T. Excretion of drugs in human milk. Am J Hosp Pharm 1974;31:84454.
- Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:13750.