I don't think it would be best to change anticonvulsants at this point,
especially as the mother's seizures are difficult to control.
Phenobarbital actually is not that big a problem, and the fact that the
mother has been on it during pregnancy means the baby will have
developed enzymes to help deal with it better once he is born.  I have
very little information about gabapentin, except that the blood levels
are low and a baby breastfeeding 1 litre a day would probably get at
most about 100 *micro*grams a day.  This is about 1% total maternal
dose, and less than he is getting in utero.

The question of in utero exposure is really two sided.  It is true that
the mother metabolizes the drug for the baby at this point.  If
accumulation of drug in the baby is the issue, then it can be argued
that what is safe during pregnancy is not *necessarily* safe during
lactation.  However, particulary with psychoactive drugs, such as
anticonvulsants, this is not the only question.  The question is whether
the baby's brain should be exposed to these drugs.  If that is the
issue, then one can definitely say that if it is considered safe during
pregnancy, it should be safe during lactation, when the baby will be
exposed to less at a less sensitive time.

Jack Newman, MD, FRCPC