Research indicates that the use of Levitra combined with Herceptin can increase the delivery of Herceptin to brain metastases without increasing delivery to surrounding healthy tissue.  The blood-brain tumour barrier is believed to have limited delivery.  A paper published on-line in PLoS One  (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010108) details the impact of combining oral Levitra with intravenous Herceptin.

Survival times increased by 20% to 30%, and tumour apoptosis (cell death) also increased.  Beneficially the Herceptin supply to healthy tissue did not increase as Levitra did not increase transmission through the blood brain barrier, only the blood-brain tumour barrier.

This research suggests that Viagra, Cialis and Levitra could be used to improve delivery of a range of therapeutics.  These drugs are helping the whole world in many ways.