Antitoxin cannot be applied unless the target is poisoned.

[Egon the Monkey]

Since its now been changed to buff with Ironguts, I reckon this is no longer a desired feature. It means you can't dose people up pre-emptively, and lessens the use of that update. Similarly it means the DC30 benefit of removing status effects won't be any use once a poison has run its course. So there's still only like a 1 minute window to use this.