Abstract
The American Academy of Pediatrics places emphasis on increasing breastfeeding in the United States. A common reason for the cessation of breastfeeding is the use of medication by the nursing mother and advice by her physician to stop nursing. Such advice may not be warranted. This statement is intended to supply the pediatrician, obstetrician, and family physician with data, if known, concerning the excretion of drugs into human milk. Most drugs likely to be prescribed to the nursing mother should have no effect on milk supply or on infant well-being. This information is important not only to protect nursing infants from untoward effects of maternal medication but also to allow effective pharmacologic treatment of breastfeeding mothers. Nicotine, psychotropic drugs, and silicone implants are 3 important topics reviewed in this statement.
INTRODUCTION
A statement on the transfer of drugs and chemicals into human milk was first published in 1983,1 with revisions in 19892 and 1994.3 Information continues to become available. The current statement is intended to revise the lists of agents transferred into human milk and describe their possible effects on the infant or on lactation, if known (Tables 1–7). If a pharmacologic or chemical agent does not appear in the tables, it does not mean that it is not transferred into human milk or that it does not have an effect on the infant; it only indicates that there were no reports found in the literature. These tables should assist the physician in counseling a nursing mother regarding breastfeeding when the mother has a condition for which a drug is medically indicated.
Cytotoxic Drugs That May Interfere With Cellular Metabolism of the Nursing Infant
Drugs of Abuse for Which Adverse Effects on the Infant During Breastfeeding Have Been Reported*
Drugs for Which the Effect on Nursing Infants Is Unknown but May Be of Concern*
Radioactive Compounds That Require Temporary Cessation of Breastfeeding*
Drugs That Have Been Associated With Significant Effects on Some Nursing Infants and Should Be Given to Nursing Mothers With Caution*
Maternal Medication Usually Compatible With Breastfeeding*
Food and Environmental Agents: Effects on Breastfeeding
BREASTFEEDING AND SMOKING
In the previous edition of this statement, the Committee on Drugs placed nicotine (smoking) in Table 2, “Drugs of Abuse-Contraindicated During Breastfeeding.” The reasons for placing nicotine and, thus, smoking in Table 2 were documented decrease in milk production and weight gain in the infant of the smoking mother and exposure of the infant to environmental tobacco smoke as demonstrated by the presence of nicotine and its primary metabolite, cotinine, in human milk.4–12 There is controversy regarding the effects of nicotine on infant size at 1 year of age.13 ,14 There are hundreds of compounds in tobacco smoke; however, nicotine and its metabolite acotinine are most often used as markers of tobacco exposure. Nicotine is not necessarily the only component that might cause an increase in respiratory illnesses (including otitis media) in the nursing infant attributable to both transmammary secretion of compounds and environmental exposure. Nicotine is present in milk in concentrations between 1.5 and 3.0 times the simultaneous maternal plasma concentration,15 and elimination half-life is similar—60 to 90 minutes in milk and plasma.7 There is no evidence to document whether this amount of nicotine presents a health risk to the nursing infant.
The Committee on Drugs wishes to support the emphasis of the American Academy of Pediatrics on increasing breastfeeding in the United States. Pregnancy and lactation are ideal occasions for physicians to urge cessation of smoking. It is recognized that there are women who are unable to stop smoking cigarettes. One study reported that, among women who continue to smoke throughout breastfeeding, the incidence of acute respiratory illness is decreased among their infants, compared with infants of smoking mothers who are bottle fed.16 It may be that breastfeeding and smoking is less detrimental to the child than bottle feeding and smoking. The Committee on Drugs awaits more data on this issue. The Committee on Drugs therefore has not placed nicotine (and thus smoking) in any of the Tables but hopes that the interest in breastfeeding by a smoking woman will serve as a point of discussion about smoking cessation between the pediatrician and the prospective lactating woman or nursing mother. Alternate (oral, transcutaneous) sources of nicotine to assist with smoking cessation, however, have not been studied sufficiently for the Committee on Drugs to make a recommendation for or against them in breastfeeding women.
PSYCHOTROPIC DRUGS
Anti-anxiety drugs, antidepressants, and neuroleptic drugs have been placed in Table 4, “Drugs for Which the Effect on Nursing Infants is Unknown but May Be of Concern.” These drugs appear in low concentrations (usually with a milk-to-plasma ratio of 0.5–1.0) in milk after maternal ingestion. Because of the long half-life of these compounds and some of their metabolites, nursing infants may have measurable amounts in their plasma and tissues, such as the brain. This is particularly important in infants during the first few months of life, with immature hepatic and renal function. Nursing mothers should be informed that if they take one of these drugs, the infant will be exposed to it. Because these drugs affect neurotransmitter function in the developing central nervous system, it may not be possible to predict long-term neurodevelopmental effects.
SILICONE BREAST IMPLANTS AND BREASTFEEDING
Approximately 800 000 to 1 million women in the United States have received breast implants containing silicone (elemental silicon with chemical bonds to oxygen) in the implant envelope or in the envelope and the interior gel. Concern has been raised about the possible effects to the nursing infant if mothers with implants breastfeed. This concern was initially raised in reports that described esophageal dysfunction in 11 children whose mothers had implants.17 ,18 This finding has not been confirmed by other reports. Silicone chemistry is extremely complex; the polymer involved in the covering and the interior of the breast implant consists of a polymer of alternating silicon and oxygen atoms with methyl groups attached to the oxygen groups (methyl polydimethylsiloxane).19 The length of the polymer determines whether it is a solid, gel, or liquid. There are only a few instances of the polymer being assayed in the milk of women with implants; the concentrations are not elevated over control samples.20 There is no evidence at the present time that this polymer is directly toxic to human tissues; however, concern also exists that toxicity may be mediated through an immunologic mechanism. This has yet to be confirmed in humans. Except for the study cited above, there have been no other reports of clinical problems in infants of mothers with silicone breast implants.21 It is unlikely that elemental silicon causes difficulty, because silicon is present in higher concentrations in cow milk and formula than in milk of humans with implants.22 The anticolic compound simethicone is a silicone and has a structure very similar to the methyl polydimethylsiloxane in breast implants. Simethicone has been used for decades in this country and Europe without any evidence of toxicity to infants. The Committee on Drugs does not feel that the evidence currently justifies classifying silicone implants as a contraindication to breastfeeding.
DRUG THERAPY OF THE LACTATING WOMAN
The following should be considered before prescribing drugs to lactating women:
Is drug therapy really necessary? If drugs are required, consultation between the pediatrician and the mother's physician can be most useful in determining what options to choose.
The safest drug should be chosen, for example, acetaminophen rather than aspirin for analgesia.
If there is a possibility that a drug may present a risk to the infant, consideration should be given to measurement of blood concentrations in the nursing infant.
Drug exposure to the nursing infant may be minimized by having the mother take the medication just after she has breastfed the infant or just before the infant is due to have a lengthy sleep period.
Data have been obtained from a search of the medical literature. Because methodologies used to quantitate drugs in milk continue to improve, this information will require frequent updating. Drugs cited in Tables 1 through 7 are listed in alphabetical order by generic name; brand names are available from the current Physicians' Desk Reference,23 USP DI 2001: Drug Information for the Health Care Professional, Volume I, 24 and USP Dictionary of USAN and International Drug Names.25 The reference list is not inclusive of all articles published on the topic.
Physicians who encounter adverse effects in infants who have been receiving drug-contaminated human milk are urged to document these effects in a communication to the Food and Drug Administration (http://www.fda.gov/medwatch/index.html) and to the Committee on Drugs. This communication should include the generic and brand names of the drug, the maternal dose and mode of administration, the concentration of the drug in milk and maternal and infant blood in relation to the time of ingestion, the method used for laboratory identification, the age of the infant, and the adverse effects. Such reports may substantially increase the pediatric community's fund of knowledge regarding drug transfer into human milk and the potential or actual risk to the infant.
Committee on Drugs, 2000–2001
Robert M. Ward, MD, Chairperson
Brian A. Bates, MD
William E. Benitz, MD
David J. Burchfield, MD
John C. Ring, MD
Richard P. Walls, MD, PhD
Philip D. Walson, MD
Liaisons
John Alexander, MD
Food and Drug Administration Alternate
Donald R. Bennett, MD, PhD
American Medical Association/United States Pharmacopeia
Therese Cvetkovich, MD
Food and Drug Administration
Owen R. Hagino, MD
American Academy of Child and Adolescent Psychiatry
Stuart M. MacLeod, MD, PhD
Canadian Paediatric Society
Siddika Mithani, MD
Bureau of Pharmaceutical Assessment Health Protection Branch, Canada
Joseph Mulinare, MD, MSPH
Centers for Disease Control and Prevention
Laura E. Riley, MD
American College of Obstetricians and Gynecologists
Sumner J. Yaffe, MD
National Institutes of Health
Section Liaisons
Charles J. Coté, MD
Section on Anesthesiology
Eli O. Meltzer, MD
Section on Allergy and Immunology
Consultant
Cheston M. Berlin, Jr, MD
Staff
Raymond J. Koteras, MHA
ACKNOWLEDGMENT
The Committee on Drugs would like to thank Linda Watson for her work in reference identification, document retrieval, and manuscript preparation.
Footnotes
The recommendations in this statement do not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.