To   : Janet Bergeson
Re   : Magnesium, Bactroban, Pepcid

Magnesium is poorly transported to milk,  reaching only sighltly higher levels
in the milk of treated patients vs untreated patients ( 6.4 vs 4.77 mg/dl
respectively).  In addition, the oral absorption of magnesium is extremely poor
and varies from 4-30% at maximum.  I seriously doubt that magnesium transport
to an infant via milk is clinically relevant.

Mupirocin(Bactroban) is not absorbed topically ( < 0.3%) and is rapidly
metabolized when ingested orally,  so it is unlikely to produce side effects in
infant.  To take this one step further,  I (being a BF bigot and dedicated to
you LCs) taste tested Bactroban to see if it would be distasteful to the
infant. It was only slightly bitter, and was not bad at all. Remember that
Bactroban is in a polyethylene glycol base which is water soluble and not a
true ointment, so it will be easily removed by water and it will not provide
much protection against friction-induced damage (like Lanolin).  As to whether
it will safeguard against mastitis is unknown.

Famotidine(Pepcid AC) as available over-the-counter is only a 10 mg dose.  The
normal therapeutic dose is 20-40 mg daily.  In one study of 8 lactating women
receiving 40 mg/day, the peak concentration in breastmilk was only 72 ug/Liter
of milk.  This dose is much lower than with Zantac and Tagamet,  and is
probably not clinically relevant.

Regards,
Tom Hale,Ph.D.