Go thru Gulf of Gunthak to the mines, there is a bruiser at that zone-in that people say drops the powder more frequently in a few posts I've seen . Lucky me, I got it first kill, but it took me a long time to kill him (til I figured out I needed KEI and Virtue as a lvl 48 BST to kill him). I had to let another bruiser who aggroed pound on me while he was running after getting below 20% to kill him, and I then looted the powder and zoned since I could not kill another at my hp and mana status.
So yes, I also believe the powder would be more frequent of a drop at the gulf of gunthak zone in, where the drop seems to favor the first bruiser. If he doesn't drop it, kill the second and then come back to him when he respawns. I doubt you need to spend 4 days elsewhere trying to get it. Plus I've seen a post saying someone killed the second spawn of the first bruiser and got the powder, so that's why I say that.
PS: Malaria spell is lvl 40, and Bond of Wild is lvl 52, as of (10/18/07). Other sites listed different lvl's when I checked.