Because there are few data regarding how much of these drugs is actually excreted in the milk, physicians err on the side of caution and advise the women to pump and discard their breast milk for 24 hours after the procedure rather than risk giving their infant an unsafe amount of the drug by way of their milk.
Michael J Avram, associate professor of anesthesiology at Northwestern University Feinberg School of Medicine, Martin Nitsun, MD, assistant professor, and colleagues from Evanston Northwestern Healthcare conducted a study that shows it is generally safe to resume breastfeeding after the most commonly used anesthetic, propofol, is administered during surgery.
Propofol is used to put patients to sleep initially as part of a general anesthetic or can be administered at a lower dose as part of a conscious sedation technique along with other intravenously administered agents, including a narcotic for pain and a benzodiazepine for amnesia.
The Northwestern researchers found that less than 0.1 percent of the dose of propofol used to put the patient to sleep appeared in her breast milk within 24 hours after drug administration because the dose is diluted by extensive distribution throughout the tissues of the body and because drug metabolism, primarily by the liver, efficiently eliminates the drug from the body.
Therefore, the very small amount of propofol eliminated in breast milk within the first 24 hours after induction of anesthesia represents such minimal infant exposure to the drug that it provides insufficient justification for interruption of breastfeeding, Avram said.
Studies of narcotic and benzodiazepine transfer into breast milk are under way at Feinberg and Evanston Northwestern Healthcare. Avram and co-researchers presented results of their study at the American Society for Clinical Pharmacology and Therapeutics annual meeting in Orlando, Florida, on March 3, 2005.