When I wanted this effect, I ended up just doing Drain Dex as a copout. That's sort of paralyzing =/
I think the book needs an specific option for paralyzing drug, like it has for mental paralysis.
This could be just be a small conditional power limitation. Something like Conditional Power: Does Not Work On Individuals With LS: Vacuum/High Pressure (-1/4). A whole -1/4 seems like a bit much for that though, unless it's more common than usual in your campaign. If it's not that common, maybe you could expand that to a slightly broader category of protective things.