Sarah:  On Oct.13, Dr. Hale posted about biaxin(clarithromycin) and
although not much data available did not seem concerned as it is a
macrolide related to erythromicin.  You might want to look at the
archives for his full reply.  He did suggest zithromax(azithromycin)
instead, since there was a study showing very low levels in milk.  My
personal bias is that erythromicin is tried and true for
bronchitis/pneumonia and AAP compatible with breastfeeding, so why use
the newer agents, unless she has an organism which is not likely to
respond to erythro (more likely if she has had recurrent episodes, is a
smoker or has underlying immunocompromise from chronic disease).  If
she's basically healthy, erythromicin would be ideal.  If there is a
reason to use one of the newer agents, then zithromax would be better.
Good luck, Alicia (she who can't understand why so many physicians
routinely use the newest medications even when the older tried and true
ones would be perfectly adequate). [log in to unmask]