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.