excellent article posted on ss - resistance, page-6

I remember some work done on making a zanamivir pro-drug, that was much more orally bioavailable, which would then become activated in the blood stream. Just had a quick google, here is the article, very high geek alert here.

Translation: Theoretically, Relenza could be made into a pill if it was chemically altered to be able to be absorbed by the stomach.
http://www.aapsj.org/abstracts/AM_2008/AAPS2008-002785.PDF