Are you sure this mother is taking 800 mg/day? This is an enormous dose.
The maximum dose in the Compendium of Pharmaceutical Specialities (Canadian
CPS is 24 mg/day).
Anyways, assuming there is an error in the reported dosage, perphenazine is
an antipsychotic like chlorpromazine, and will likely increase milk supply.
The baby will get small amounts in the milk, but not as much as he got
during the pregnancy. Watch for sedation, but it is unlikely to happen.
Jack Newman, MD, FRCPC