In the references section of the book, it mentions an article in the American Journal of Gastroenterology, 2007, 102 (9): 2036-45.
A second article referenced is in: Drugs, 1998, 56 (3): 429-45
A third is: Amer. Journ. of Gastroent. 1997, 92 (6): 976-80
About 1% of your intake of dom. will get into the milk. As Dr. Newman points out, from the baby's perspective, it is well worth a very small exposure to a relatively safe drug in order to gain precious breastmilk. In other countries, dom. is sometimes prescribed for babies at much higher doses than your breastmilk would contain.
Hope that helps-Jennifer in MI