To Dr. Ahrendsen:

        Re your question on Valproic acid.  A really good review of  11
women given valproic acid both before and after delivery is provided by Nau,
H,   J.Pharmacology and Exp. Therap. 219: 768, 1981.   In this review,  they
noted that the fetal plasma levels were significantly higher than  the
maternal plasma level,  suggesting significant concentrations sequester in
the fetus.  In addition the fetal half-life was 4 times longer than the
maternal half-life.  However,  upon delivery,  the amount of valproic acid
distributed to the infant via breastmilk  varied depending on the patient
from  1-10% of the maternal serum levels(averaged 3%).  The authors
suggested that using valproic acid in BFing moms was apparently safe.  The
average milk concentration in these moms was 1.4 micrograms /ml milk.   From
these studies,  they found that the infants plasma levels were only 10-15%
of the mom's plasma level.

        Note that soon after birth,  the moms' doseage needs adjustment
downward,  as her metabolism of the drug reduces after delivery.  If
needed,  the infant's plasma levels can be monitored.  Timing is of course
important,  I would wait several weeks to get a good estimate of the infants
steady state plasma level(T1/2 = 47 hrs).

        So I think with occassional monitoring of blood levels and maybe
liver enzymes,  it would appear valproic acid therapy in BFing moms is
reasonably  safe.


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T.W. Hale, Ph.D.
Associate Professor of Pediatrics
Texas Tech University School of Medicine

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