Modifying Salvinorin A -- Stopping BBB Crossing

[Nathanial.Dread]

Can anyone think of any simple modifications one could do to the salvinorin A molecule that would keep it from crossing the blood-brain barrier? I'm not much of a medicinal chemist, but I've been having some interesting thoughts about possible uses for such a compound. Possibly by sticking some large halogen on one end, making it less lipophillic?

Blessings
~ND

 

[kerelsk]

Thought somebody might have looked into this "sort" of molecule before and lo:
Asimadoline - Wikipedia

 

[Nathanial.Dread]

Damnit. I thought I was going to make so much money