US Pharm.
2007;32(9):10-14.
It is considered unethical for
manufacturers to design prospective human trials to ascertain potential
teratogenicity or to determine dangers to a baby when medications pass into
breast milk.1 Thus, pregnant and lactating females are often
referred to as therapeutic orphans. Many of these patients choose
nonprescription products on their own.2 However, even when women do
ask, pharmacists are hampered by the general lack of knowledge regarding the
potential dangers of these products.
Pregnancy Versus Lactation
While pregnancy and
lactation may seem similar with regard to medication toxicities, there are
fundamental differences. During pregnancy, the fetus can come into contact
with medications in higher amounts than through lactation.3 Despite
this, the mother's liver and kidneys aid in detoxification and excretion.
However, although less medication reaches the breast-feeding child, the infant
must rely on its own detoxification and excretion abilities. Thus, each
situation presents a unique set of problems.
Pregnancy
The risk for major
malformations in babies is 3%, most of which are unrelated to medication
ingestion.1 Nevertheless, pregnant females are usually careful to
do everything possible to deliver a healthy infant. This should include
abstaining from drugs of abuse and restricting use of medications that are not
prescribed. The well-known thalidomide incident is still in the public
awareness.3,4 Definitive evidence regarding other medications is
usually lacking, as it is unethical to administer any product to pregnant
females to determine teratogenicity. The identification of a possible
teratogen usually rests on case reports, case-controlled studies, or cohort
studies.3 Fortunately, few medications are teratogenic.
Aspirin and other NSAIDs are
nonprescription products that are known teratogens, as they affect the fetal
cardiovascular system. These products should be avoided during the last
trimester. Furthermore, aspirin and other salicylates can cause alterations in
maternal and fetal hemostasis mechanisms, decreased birth weight, and
increased perinatal mortality.5 If aspirin is given one week before
or during labor and delivery, it can result in excessive blood loss at
delivery. Its action in inhibiting prostaglandin may also prolong labor and
gestation.
The FDA has developed
pregnancy risk categories.4,6 Category A (remote risk of harm in
controlled studies in women) includes vitamins at RDA doses. Category B (no
apparent harm to the fetus in animal and/or human research) includes
acetaminophen, cimetidine, aluminum hydroxide, insulin, and ibuprofen in the
first and second trimesters. Category C (no well-controlled studies in
pregnant women) includes pseudo ephe drine, simethicone,
clotrimazole, senna, dextromethorphan, aspirin, and hydrocortisone in the
second and third trimesters. Category D (positive evidence of human fetal
risk, but benefits may outweigh risk) includes ibuprofen in the third
trimester and hydrocortisone in the first. Category X, including vitamin A at
doses over the RDA, is contraindicated in pregnant women and in those who may
become pregnant.
Breast-Feeding
The majority of
prescription and nonprescription medications are not found in breast milk
after ingestion.2 However, there are several recommendations that
can be given to the concerned mother.2 First, she should be
encouraged to avoid medications whenever possible and to explore the option of
nonpharmacological therapies. Second, she should be advised to take oral
medications immediately after nursing the infant and preferably before the
babylongest sleep period. This will help prevent the baby from encountering
medications by avoiding peak plasma and breast-milk levels. Third, the mother
should take the regular-strength versions of a nonprescription product, rather
than extra strength, maximum-strength, or long-acting versions. The mother
should rely on single-entity medications instead of combinations, and she
should be alert for the first sign of an adverse event in order to notify the
pediatrician as early as possible.
Analgesics:
Aspirin, magnesium salicylate, and bismuth subsalicylate can enter breast
milk; they can cause adverse effects and lead to Reye's syndrome.2
Aspirin in breast milk can also cause rashes, platelet abnormalities, and
bleeding.5 Combination analgesic products containing
diphenhydramine, phenyltoloxamine, caffeine, salicylamide, and other
ingredients should be avoided. Safer alternatives are ibuprofen and
acetaminophen.
Antihistamines and
Decongestants:
Clemastine may produce drowsiness and irritability in the breast-fed infant.
2 Other antihistamines may also cause drowsiness. Experts advise
ingesting the antihistamine after the last nighttime feeding, just prior to
bedtime.2 Pseudoephedrine passes poorly into breast milk (0.5% of
the oral dose), although it may decrease the volume of breast milk.2,7
Oxymetazoline can decrease milk supply.2 Phenylephrine has a
shorter duration of action and might be preferable as a topical nasal
decongestant, although mothers should carefully monitor the volume of breast
milk to ensure that it does not undergo appreciable reduction in volume.2
Cough and Sore Throat
Products:
Guaifenesin, dextromethorphan, menthol, dyclonine, and benzocaine are
reportedly safe for use by breast-feeding mothers.2 Although
codeine does reach breast milk in detectable amounts, dextromethorphan is a
safer antitussive.
Gastrointestinal
Products: For upset
stomach or reflux, antacids containing calcium or magnesium are fairly safe,
as little passes in breast milk.2 However, sodium-containing
antacids (e.g., Alka-Seltzer, Bromo-Seltzer) could cause fetal accumulation
and should be avoided. Of the nonprescription H2-antagonists,
cimetidine and ranitidine are found in higher concentrations in breast milk
than famotidine and nizatidine, making the latter two appear preferable.2
Antidiarrheals containing loperamide are acceptable, but bismuth
subsalicylate products should be avoided to prevent Reye's syndrome. For
constipation, preferred agents are the bulk-forming products such as psyllium
or methylcellulose. Magnesium hydroxide (e.g., Freelax) would also be
acceptable, but docusate may cause diarrhea in the infant, and stimulants such
as senna and bisacodyl are less optimal choices for all patients because of
their nonphysiologic action. Simethicone is safe for flatulence because it is
virtually unabsorbed by the mother.
Herbal Medicines and Other
Dietary Supplements
Approximately 13%
of pregnant women take herbs or dietary supplements (other than vitamins or
folic acid).8 Dietary supplements comprise unproven products such
as herbals and nonbotanical supplements. (Homeopathic products are also
unproven.) The FDA does not have the power to force manufacturers to prove
these products are safe or effective for use, and their safety in pregnancy
and breast-feeding is virtually unknown.9,10
As an example of possible
hazards of dietary supplements, an infant suffered focal seizures 26 hours
after birth and was found to have an infarct in the left-middle cerebral
artery.11 The mother reported ingestion of blue cohosh tea as a
means to induce labor. Manufacturers of blue cohosh (and all other herbs) do
not carry out systematic studies of their use in pregnancy or lactation.
Cerebral infarcts are exceedingly rare in newborns, but blue cohosh is known
to cause uterine contractions and vasoconstriction, making it a possible
cause. Furthermore, an older report pointed to blue cohosh tea as the
causative factor in a neonate who experienced congestive heart failure, shock,
and myocardial infarction.12 While some argue that such case
studies should not be used to issue blanket indictments against all unproven
products in pregnancy, others point out that the "poor quality control,
uncertain efficacy and unknown dangers" of herbal medicines creates an
unfavorable risk–benefit ratio with their use.13,14
A series of articles in The
Canadian Journal of Clinical Pharmacology explored several herbs' safety
and efficacy during pregnancy and lactation. One reported that 45% of midwives
use black cohosh to induce labor, but that its use should be discouraged in
all pregnant patients due to such concerns as labor induction prior to the
appropriate time, hormonal effects, emmen ogogue (promoting menstrual
flow) properties, and anovulatory effects.15 Its possible
estrogenic/antiestrogenic effects would also cause it to be contraindicated in
breast-feeding. Another article examined echinacea, concluding that it may be
safe during pregnancy, but insufficient evidence exists to recommend its use
while breast-feeding.16 St. John's wort is of unknown safety during
pregnancy, and use while breast-feeding may cause colic, drowsiness, and
lethargy.17 Ginkgo should be avoided during pregnancy because of
its ability to prolong bleeding time; its safety during lactation is unknown
and it should not be ingested.18 These reports exploring the safety
of herbs in pregnancy and lactation are the exception rather than the rule for
dietary supplements.
Taiwanese researchers
conducted a prospective study in which over 14,000 live births were examined
in relation to maternal ingestion of herbs.19 The herb huanglian
was associated with major congenital malformations of the nervous system and
An-Tai-Yin with major malformations of the musculoskeletal and connective
tissues and the eye.
Each dietary supplement should
be subjected to the same type of analysis to determine teratogenicity, but
this is seldom done. Thus, pharmacists should advise against use of herbs and
dietary supplements in pregnant and nursing patients.
References
1. Kyle PM. Drugs and the fetus. Curr Opin Obstet Gynecol. 2006;18:93-99.
2. Nice FJ, Snyder JL, Kotansky BC. Breastfeeding and over-the-counter medications. J Hum Lact. 2000;16:319-331.
3. Della-Giustina K, Chow G. Medications in pregnancy and lactation. Emerg Med Clin North Am. 2003;21:585-613.
4. Lee E, Maneno MK, Smith L, et al. National patterns of medication use during pregnancy. Pharmacoepidemiol Drug Saf. 2006;15:537-545.
5. Final rule for professional labeling of aspirin, buffered aspirin, and aspirin in combination with antacid drug products. Fed Reg. 1999;64:49652-49655.
6. McCarter-Spaulding DE. Medications in pregnancy and lactation. MCN Am J Matern Child Nurs. 2005;30:10-17.
7. Hale TW. Medications in breastfeeding mothers of preterm infants. Pediatr Ann. 2003;32:337-347.
8. Fast facts about medication use during pregnancy and while breast feeding. Centers for Disease Control and Prevention. Available at: www.cdc.gov/ncbddd/meds/fast.htm. Accessed August 2, 2007.
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15. Dugoua JJ, Seely D, Perri D, et al. Safety and efficacy of black cohosh (Cimicifuga racemosa) during pregnancy and lactation. Can J Clin Pharmacol. 2006;13:e257-261.
16. Perri D, Dugoua JJ, Mills E, et al. Safety and efficacy of echinacea (Echinacea angustifolia, E. purpurea and E. pallida) during pregnancy and lactation. Can J Clin Pharmacol . 2006;13:e262-267.
17. Dugoua JJ, Mills E, Perri D, et al. Safety and efficacy of St. John's wort (hypericum) during pregnancy and lactation. Can J Clin Pharmacol. 2006;13:e268-276.
18. Dugoua JJ, Mills E, Perri D, et al. Safety and efficacy of ginkgo (Ginkgo biloba) during pregnancy and lactation. Can J Clin Pharmacol. 2006;13:e277-284.
19. Chuang CH, Doyle P, Wang JD, et al. Herbal medicines used during the first trimester and major congenital malformations: An analysis of data from a pregnancy cohort study. Drug Saf . 2006;29:537-548.
20. Qu F, Zhou J. Treating threatened abortion with Chinese herbs: A case report. Phytother Res. 2006;20:915-916.
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