To : Dr. Newman Re : Peripheral disposition of Paroxitine As per your question concerning paroxitine: You are correct that it could be more of a problem in a pregnant women, but in this situation, at least the maternal metabolism will prevent a high level(toxic) in both mom and fetus, as they are to some degree in equilibrium. As for fentanyl, this is exactly what is happening, the mom's plasma is pumping tons of fentanyl to the infants' plasma, which then sequesters the fentanyl in tissue. Upon birth, the infant is sedated. However, postpartum, where the newborns levels are determined by his/her own clearance, it is conceivable for levels to continue to build up and become even more of a problem, but generally only for drugs with long half-lives and poor clearance. This is probably why we have a number of published papers on Prozac(fluoxetine) suggesting significant plasma levels in breastfed infants, because its active metabolite has a half-life of about 240 hours, and the infant simply can't get rid of it quick enough. As for paroxetine(Paxil), the fact that it has a relative shorter half-life, and that the concentration in milk is presumably quite low, the infant can probably clear enough that long term buildup in the tissue compartments is probably quite low... which makes this a preferred drug in comparison to fluoxetine. Regards Tom Hale