For tonics you can use in explorable areas, you can:
1) drink one
2) go through a portal (e.g. the one going to the tutorial area in PvP for example)
3) drink one
4) hit s and w (turn around, and run forward) to go through a portal
5) repeat 3-4 as needed
That is slightly faster than map travel.
Tonics only usable in town, perhaps the jade quarry etc (these have two outposts connected, one PvE the other PvP).