As a pharmacist specializing in psychopharmacology, I am commonly consulted by psychiatrists to provide updated information on the safety of medications in pregnancy and breastfeeding. It is a difficult task, because the quantity and quality of data for medications vary greatly. I developed the accomanpanying table for TCPR readers by pulling together a variety of sources, including isolated case reports, case series, birth registries, retrospective surveys, prospective comparative cohort studies, case control studies, and meta-analyses. Making judgments about which medication to use—or not use—in pregnant or lactating women is a delicate balancing act, involving an assessment of the severity of the underlying illness versus the uncertainties inherent in prescribing medications when the available data are limited.

In reading the following table, keep the following in mind: In the general U.S. population, the baseline rate of major malformations is between one and four percent, depending on the population studied and the definitions of “malformations” used. If treatment is necessary, monotherapy with the lowest effective dose and for the shortest duration is prudent. Safety data is generally more robust with older agents, which are more preferable to use than newer agents with less established safety profiles.

Almost all drugs will enter breast milk. The exposure to the infant is described as a percentage of the maternal dose—that is, how much of the dose is actually excreted into the breast milk. When less than 10% of a mother’s dose of medication is excreted into the breast milk, it is generally considered compatible with breastfeeding (with some exceptions) since these low serum levels are unlikely to lead to adverse effects in the infant.

For more information, I recommend checking out the websites for Motherisk, a resources for professionals and patients, at www.motherisk.org (see “Drugs in Pregnancy” and “Breastfeeding and Drugs” links); and LactMed database of the National Library of Medicine at http:// bit.ly/dybfhM.

See comprehensive psychotropics in pregnancy and breastfeeding chart here.

Additional References:
Cohen LS et al, Psychiatr Clin N Am 2010;33(2):273–293
Einarson A, Can J Clin Pharmacol 2009;16(1):e58–e65
Gentile S, Schizophrenia Bulletin 2010;36(3):518–544
Menson SJ, Arch Gynecol Obstet 2008;277:1–13
Myla ME, Can J Clin Pharmacol 2009;16(1):e49–e57
Yonkers KA et al, General Hospital Psychiatry 2009;31(5):403–413