I recently reviewed the radiocontrast agents for a certain(unmentionable)
book.  As there is nothing published concerning milk levels,  we have to use
some intuition instead.  Simply put,  the radiocontrast agents such as
Telepaque, Omnipaque, Cholebrine, Bilivist, Hypaque , etc. etc.  are
chemical substances that have a large proportion of their molecular weight
due to covalently bound Iodine.  As you should know,  Iodine is a specific
problem in breastfeeding moms due to iodine trapping in milk(M:P ratios as
high as 26).    So I contacted a number of the companies who make the
radiopaque agents,  asked for the kinetics of metabolism and found that
almost without exception,  the above agents are rapidly cleared from the
plasma compartment,  completely unmetabolized.  Here are some relevant facts:


       1) First,  they are rapidly injected IV.  They seldom leave the
plasma compartment but instead are rapidly excreted by the kidney.  Their
iodine content and their  retention in the plasma compartment accounts for
their radioconstrast properties.   Their plasma half-lives vary from 20-90
minutes,  very short indeed.

        2)  According the several manufactures,   less than  0.005% of the
iodine is cleaved from the benzene rings and is free to permeate to milk.
This is good,  because the iodine remains bound to the molecule and is
subject to a very rapid elimination via the kidney.   So its in and out real
quick.  Great for breastfeeding moms.

        3)  Even the manufactures generally suggest that a breastfeeding mom
discontinue only 24 hours,  before reinitiating  breastfeeding.  Even this
is probably not required,   because when orally administered,  these agents
are not absorbed into the circulation.  They are sometimes even used as
contrast agents for  GI evaluations in newborns.

        Taken as a whole,  this group of agents seem to have a very low
degree of toxicity,  and are probably quite safe to use in breastfeeding
mothers.  I would attempt to wait 4-5 half-lives and then restart feeding.
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T.W. Hale, Ph.D.
Associate Professor of Pediatrics
Texas Tech University School of Medicine

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