Medications and Mothers' Milk
Santa Clarita CA USA
Report on a session from the 2003 LLLI Conference
From: NEW BEGINNINGS, Vol. 20 No. 5, September-October 2003, pp. 175
As a pioneering researcher in lactational pharmacology, Thomas Hale, RPh, PhD is recognized around the world as the expert on the transfer of medications and other substances into human milk. At the La Leche League International Conference, Dr. Hale presented an introduction to lactational pharmacology, examples of the behavior of many common medications in human milk, and some of the latest research.
Dr. Hale began by explaining some of the basic elements of the hormonal and anatomical structure of milk production. In describing the general relationship between the mother's bloodstream and milk-producing cells, he asserted that the alveolar cells resist letting medications pass through to milk and the level of medications found in a mother's milk will remain in equilibrium with the level in the mother's plasma. He stated that in general, 90 percent of medications pass less than one percent of the mother's dose to the baby through human milk.
As a way to avoid giving a concentrated dose of medication to the baby through human milk, Dr. Hale advised to "avoid the peak." Since most drugs have a peak concentration in the bloodstream between one and one-and-a-half hours after administration, breastfeeding just before or two to four hours after taking a medication usually delivers the lowest level of medication to the baby. Dr. Hale suggests using medications with a short half-life, which means the medication enters and exits the mother's bloodstream more quickly. Medications with a long half-life remain in the mother's bloodstream and milk supply much longer.
Dr. Hale continued with descriptions of several common types of drugs, explaining their behavior in the mother's body and advising caution with several. He suggests that mothers obtain as much data on the prescribed drug as possible and share this information with the health care provider. He also suggests watching baby closely when taking any kind of medication.