Safety in Lactation: Drugs affecting bone metabolism

Laura Kearney, Regional Principal Medicines Information Pharmacist, Midlands and East Medicines Advice Service (Midlands site) & UK Drugs in Lactation Advisory ServicePublished

Drugs used exclusively for postmenopausal osteoporosis have not been included.
Bisphosphonates have very poor oral bioavailability in fasting adults, which is decreased even further in the presence of food. Therefore, breast milk is expected to contain negligible amounts of a bisphosphonate, which will be strongly bound to breast milk calcium. However, bisphosphonates are taken up into bones, from which they are released only slowly (several days to weeks). It is, therefore, theoretically possible that the longer term exposure of infants to very small amounts in breast milk could affect the infant’s calcium status and subsequent bone development, although this is considered unlikely. In general, bisphosphonates are considered to be compatible with breastfeeding and routine monitoring of infant calcium levels unnecessary unless others factors are present which could affect calcium status.