Knowing drugs in general, that wouldn't really be of any benefit. It would most likely be directly injected into the bloodstream, any vein like an IV bag or anesthesia.

You may be thinking about how it's been rumored/theorized to be extracted from the victims, which is using a syringe to directly extract it from the brain stem or some other part of the body while they're alive. I haven't seen any direct evidence that that is the case, but then again I don't think I'd want to.