The American Academy of Pediatrics (AAP) periodically publishes clinical reports, which contain guidance for clinicians whose patients fit into a particular category. Previously published clinical reports include The Prenatal Visit (for expectant mothers) and Health and Mental Health Needs of Children in US Military Families. These clinical reports are published in Pediatrics, the official journal of the AAP.
A clinical report published today, August 26th, 2013, provides updated information for clinicians advising new mothers on breastfeeding. Entitled The Transfer of Drugs and Therapeutics into Human Breast Milk: An Update on Selected Topics, the report covers several categories of drugs that may be transferred into breast milk. Perhaps because of the opening lines of the abstract ("Many mothers are inappropriately advised to discontinue breastfeeding or avoid taking essential medications because of fears of adverse effects on their infants"), some media outlets have interpreted the AAP's guidance as emphasizing a lack of potential harm for nursing infants from most drugs.
It is true that the report's authors, Hari Cheryl Sachs and the AAP Committee on Drugs, state that "only a small proportion of medications are contraindicated in breastfeeding mothers or associated with adverse effects on their infants." However, referring to the number of drugs that can be damaging as a proportion of all existing medications is somewhat misleading. For example, the report lists many psychoactive drugs as "approach[ing] clinically significant levels," including buproprion (often marketed as Wellbutrin or Zyban), diazepam (initially sold as Valium), fluoxetine (often marketed as Prozac), citalopram (an SSRI often sold as Celexa), lithium (generally prescribed as lithium carbonate), lamotrigine (marketed by GSK as Lamictal), and venlafaxine (an SNRI known as Effexor). All of these drugs are quite popular, with sales in billions of doses per year. Indeed, the CDC reports that nearly 10% of American women ages 18 to 39 are currently taking an antidepressant medication. Rather than viewing these seven drugs as merely seven formulations in a universe of thousands, it might be more prudent to consider them as products consumed by roughly 10% of potentially breastfeeding women.
Perhaps of greater concern is the report's admission that "data on drug excretion in human milk are not available for up to one-third of psychoactive therapies." Given the data that does exist on some psychoactive drugs, it does not seem wise to assume the absolute safety of these unknown-transfer drugs for nursing infants.
The report sounds a note of caution with respect to several narcotics, such as codeine, as well. "Normal doses of codeine given to lactating women may result in dangerously high levels of its active metabolite morphine in breastfeeding infants," Dr. Sachs and her colleagues report. When it comes to non-steroidal anti-inflammatory drugs (NSAIDs), another popular class of drugs, the report is similarly prohibitive: "Limited published data on ... etodolac [often called Lodine], fenoprofen [sold in the UK as Fenopron], meloxicam [sold as Mobic], oxaprozin [popularly known as Daypro], piroxicam [sold by Pfizer as Feldene], sulindac [sold by Merck as Clinoril], and tolmetin [marketed as Tolectin]... are available, and FDA labeling discourages their use." Indeed, although the AAP does not view naproxen (popularly known a Aleve) as incompatible with breastfeeding, the report's authors note that "long-term use of naproxen is not recommended because of the drug's long half-life and case reports of gastrointestinal tract bleeding and emesis [vomiting]." The report goes on to recommend against taking several other categories of popular drugs while nursing.
Given the high percentage of popular drugs contraindicated for breastfeeding mothers, a prudent course of action for physicians and their patients is to consult the LactMed database created as part of ToxNet, part of the National Libraries of Medicine. However, even this database is not flawless; a quick search for one drug known to be transferred in large quantities to breast milk, Lamictal, turns up the following sentence: "Three women with bipolar disorder breastfed their infants during pregnancy and breastfeeding." As it is virtually impossible to breastfeed an infant during pregnancy -- and breastfeeding during breastfeeding is a tautology -- it is evident that more care could have been taken with the compilation of NLM's report on Lamictal. Certainly, more care should be taken by new mothers concerned about passing drugs to their infants.