Bismuth subsalicylate, metronidazole, and tetracycline Pregnancy Warnings
Animal models given tetracycline have revealed evidence of reversible decreases in skeletal formation, yellow discoloration of bones and teeth, and embryotoxicity (when given early in development). Animal models given oral metronidazole have failed to reveal evidence of fetotoxicity; when given intraperitoneally, intrauterine deaths occurred. Animal studies with bismuth subsalicylate potassium have not been reported. There are no controlled data in human pregnancy.
There are case reports of bone and teeth yellowing in infants exposed to tetracycline during the second and third trimesters; there are also reports of decreased fibula growth in premature infants which resolved upon drug discontinuation. Metronidazole has been evaluated in over 5000 pregnant women.
US FDA pregnancy category D: There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
The manufacturer makes no recommendation regarding use during pregnancy.
US FDA pregnancy category: D
Comments:
-If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus.
-Use of adequate methods of contraception should be encouraged.
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Bismuth subsalicylate, metronidazole, and tetracycline Breastfeeding Warnings
A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.
Excreted into human milk: Yes (metronidazole and tetracycline); Unknown (bismuth subsalicylate)
Excreted into animal milk: Data not available (bismuth subsalicylate)
Comments:
-The effects in the nursing infant are unknown.
-Patients should discard milk produced during treatment and 24 hours after completing treatment; infants should be fed stored milk (collected prior to treatment) and/or formula.
The effects of this drug on milk production are unknown.
Metronidazole is potentially tumorigenic and is known to be excreted into human milk. Infant metronidazole serum levels may be close to or comparable to therapeutic levels.
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