Felbamate has some disadvantages with regard to breastfeeding in that
it has a long half life, relatively low protein binding and high oral
biovailability.

Nevertheless maternal levels are low, as with all drugs, and the baby
will probably have developed the enzymes to metabolize it because of
exposure during pregnancy.

One wonders why it is okay to expose the baby during pregnancy, but
not during lactation, when the baby is more mature and getting less.
It's true that the baby has no maternal liver to metabolize the drug
for him, but...

Overall, this is a difficult one to say with any assurance.  However,
not breastfeeding carries certain risks which are likely to override
any concern about the drug.  The mother is the one who, given
information to make an informed choice, makes the choice.

Jack Newman, MD, FRCPC