Background: The benefits of breastfeeding for both mother and infant are well documented. The World Health Organization recommends exclusive breastfeeding for the first four to six months of life and its continuation for one to two years thereafter. Advocacy for breastfeeding has led to increased breastfeeding rates worldwide; however, more than 50 percent of breastfeeding women take some sort of drug, and data on excretion of drugs into breast milk and possible effects on infants are often limited or unavailable. This uncertainty is especially true of psychotropic medications. Psychiatric disorders complicate an estimated 500,000 pregnancies in the United States annually; therefore, more accurate drug data are needed to better evaluate the safety of psychotropic medications in newborns. Fortinguerra and colleagues systematically reviewed the literature to provide updated and more comprehensive data on infant exposure and adverse events to various categories of psychotropic medications.

The Study: The authors evaluated original and review articles retrieved through Medline (1967 through July 2008), EMBASE (1975 through July 2008), and PsychINFO (1967 through July 2008); all bibliographies from these articles were also searched to determine additional pertinent studies. The manufacturers were contacted directly for information on drugs that had no published studies. The following data were included from reviewed articles: maternal dosage; number of mother-infant pairs studied; the milk-to-plasma ratio; the relative infant dosage received through breast milk; and infant adverse events. To determine each drug's compatibility with breastfeeding, the pharmacokinetic characteristics, excretion in breast milk, number of treatment days at sampling, and the incidence and type of adverse events in infants were considered. Drugs were categorized in the following way: as compatible if the relative infant dosage was less than 10 percent of the maternal dosage and no adverse events were reported; as a caution drug if there were no available data to confirm the safety or risk of the accumulated drug with prolonged use; or as contra-indicated if the relative infant dosage was more than 10 percent of the maternal dosage and adverse events were reported in breastfed infants.

Results: The literature review produced 183 original articles for evaluation, which revealed data for 62 of the 96 psychotropic drugs. The remaining 34 medications had no data (including from the manufacturers) on their safety in breastfeeding and were considered contraindicated. Of the 62 drugs for which there were data, 15 were contraindicated because of elevated exposure levels or adverse events in infants. Consequently, 19 drugs can be used during lactation, and 28 have insufficient data to evaluate. Among the drug subclasses, selective serotonin reuptake inhibitors were most thoroughly studied; because of their low level of excretion in breast milk, sertraline (Zoloft), paroxetine (Paxil), and fluvoxamine were found to be first-choice medications for breastfeeding mothers. Conversely, citalopram (Celexa), escitalopram (Lexapro), and fluoxetine (Prozac) were contraindicated because of a longer half-life, adverse effects, and a higher relative infant dosage (see accompanying table).

Conclusion: The authors conclude that safety data for psychotropic medications in breastfeeding vary widely. Although many of these drugs are compatible with breastfeeding, no class effect applies, so potential pharmacologic therapies need to be addressed on an individual basis.