Dear Dr. Nice, 
Thank you for contacting the Division of Drug Information in the FDA's Center for Drug Evaluation and Research.  Your inquiry was forwarded to the Division of Reproduction and Urology Products for  comment.  Please refer to the following below response from the review division: 

Our recent Methergine labeling changes concerning breast feeding were based on the following information and rationale:
 
 We did not differentiate between "chronic" (assumed this to mean multi-dose) versus "acute" (assumed this to mean a single dose) use, because we do not have data to support safety of single dose over multiple dose.  Although the isolated cases of neonatal adverse outcomes (e.g. seizures, bradycardia, unstable blood pressure) were reported in infants of mothers ingesting methergine for more than one day, the PK data showed that methergine is present in breast milk after a single dose.  
 
2. The published article on PK parameters of methergine in breast milk showed the mean half-life of methergine in breast milk to be 2.3 hours (Vogel et al., 2004)  .  We agreed with the sponsor's proposed 12 hour delay, because five half-lives (2.3 hrs x 5 ~ 12 hours) usually ensures that methergine would no longer be present in the breast milk.
 We appreciate  your commitment to public health.  
Sincerely,  
Division of Drug Information
Center for Drug Evaluation and Research
Food and Drug Administration
kcd
For up-to-date drug information, follow the FDA's Division of Drug Information on Twitter at FDA_Drug_Info 
This communication is consistent with 21CFR10.85(k) and constitutes an informal communication that represents our best judgment at this time but does not constitute an advisory opinion, does not necessarily represent the formal position of the FDA, and does not bind or otherwise obligate or commit the agency to the views expressed.


Frank J. Nice, RPh, DPA, CPHP
 		 	   		  
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