8. A donor who is lactating must be willing and able to interrupt breast-feeding or substitute formula feeding for her infant during the period of filgrastim administration and for two days following the final dose. Filgrastim may be secreted in human milk, although its bioavailability from this source is not known. Limited clinical data suggest that short-term administration of filgrastim or sargramostim to neonates is not associated with adverse outcomes.