WRITER: MEGHAN NEARY
CONTACT: DAVE PEDERSEN
Iowa City IA 52242
(319) 335-8032; fax(319) 335-8034
Release: Nov. 14, 2000
UI researcher investigates anti-depressants and nursing mothers
IOWA CITY, Iowa -- University of Iowa Health Care researchers are looking
into the effects of antidepressants on the infants of nursing mothers with
Numerous studies have been conducted to gauge the extent of exposure of
antidepressants in infants of nursing mothers. These studies are intended
to provide descriptive data to aid physicians when making the choice of whether
or not to prescribe an antidepressant to a breastfeeding mother. The studies
have shown that some antidepressants showed higher levels of accumulation
in infants' blood. It should be noted that these studies were conducted with
a small number of infants, often three or fewer.
A current study headed by Alicia Weissman, M.D., in the University of Iowa
Department of Family Medicine involves mothers with postpartum or other depression
who have taken one or more antidepressants for at least one week. Weissman
and her colleagues measure the amounts of various antidepressants in blood
samples from both the mother and infant, and in samples of the mothers' breast
milk. These measurements are made in an attempt to discover which antidepressants
tend to accumulate in the infant's bloodstream and which ones do not.
Because antidepressants must get into the brain, they pass through the blood-brain
barrier, a protective membrane that protects the brain from being exposed
to everything that passes through the bloodstream. The same characteristics
that allow a drug to pass through the blood-brain barrier also allow the drug
to pass into breast milk. Weissman says that all antidepressants will enter
"The issue is not whether or not the drug gets in, it's how much and
whether it builds up in the baby," she said.
Weissman added that the drug levels in breast milk are not necessarily predictive
of the drug levels in an infant. Factors such as the infant's metabolism and
the half-life of the drug, or how long it remains in the infant's system,
will also affect the levels.
However, Weissman says antidepressants and other substances may accumulate
in newborns, who do not have the liver capacity of adults. This is because
the liver is responsible for filtering substances that enter the bloodstream.
By looking at the levels of antidepressants in nursing mothers, their breast
milk and their newborns, Weissman and her colleagues hope to determine which
antidepressant medications may be better suited for nursing mothers.
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