Metronidazole excretion in human milk and its effect on the suckling neonate.

Abstract

1. Milk and plasma metronidazole and hydroxymetronidazole concentrations were measured in 12 breast‐feeding patients following multiple doses of metronidazole (400 mg three times daily). All patients received metronidazole in combination with other broad spectrum antibiotics. 2. Plasma concentrations of both parent drug and metabolite were measured in seven suckling infants. Thirty‐five infants were monitored for adverse reactions to maternal metronidazole therapy and two further groups of suckling infants, those whose mothers received either ampicillin alone or no drug therapy, were recruited as controls. 3. The mean milk to plasma ratio (M/P) was 0.9 for metronidazole and 0.76 for hydroxymetronidazole while the mean milk metronidazole concentrations (around Cmax) were 15.5 micrograms ml‐1. The mean milk hydroxymetronidazole concentration was 5.7 micrograms ml‐ 1. 4. Infant plasma metronidazole concentrations ranged from 1.27 micrograms ml‐1 to 2.41 micrograms ml‐1, and the corresponding hydroxymetronidazole concentrations from 1.1 to 2.4 micrograms ml‐1. 5. There were no significant increases in adverse effects in infants which could be attributable to maternal metronidazole therapy. 6. Metronidazole was excreted in milk at concentrations which caused no serious reactions in the infants studied. The drug may therefore be administered at doses of 400 mg three times daily to mothers wishing to breast‐feed their infants.

Antibiotics and Breastfeeding

“…Studies in mothers treated with the drug at doses of 400 mg 3 times daily demonstrated that concentrations in breast milk ranged up to 15 μg/ml. The assessment of metronidazole levels in infant plasma revealed concentrations of 1.27-2.41 μg/ml, with no appearance of adverse effects in these infants [98]. Other studies that used the same methodology reported similar results [99].…”

Pregnancy and Crohn’s Disease

“…Metronidazole [23, 24] and ciprofloxacin [25] are excreted into breast milk, but only scant data are available [24] about their safety for breast-fed infants.…”

Pregnancy and Breastfeeding in Patients with Crohn’s Disease

“…Metronidazole [35, 36] and ciprofloxacin [37] are excreted into breast milk, but only scant data are available about their safety for breastfed infants (table 2). The Committee on Drugs of the American Academy of Pediatrics [38] classify metronidazole as a ‘drug for which the effect on nursing infants is unknown but may be of concern’ and ciprofloxacin as a ‘maternal medication usually compatible with breastfeeding’.…”