I was wondering if you had come across this GHB effect... I very nearly ODed myself taking GHB of *known* concentration [I made it myself] because [I'm guessing here] the stuff I decanted into a smaller bottle for travelling was from the bottom of the larger container and the stuff at the bottom was more GHB-rich that the stuff at the top. Basically I took what should have been a mild dose [2 grams, I generally take 2.5-ish and have for months now] and found myself almost immediately going into seizure and then the pesky unrouseable coma for nearly five hours.
I was taken to the hospital & intubated/ventilated. They kept me for three days because of the seizures. I came out of it just fine. I even told them what I had been on and they said they have never heard of it [this was in Indiana].
Long story short, I was ok, but very surprised at the negative effect because I'd been so careful with measurement. Other, earlier-filled containers from the same larger bottle seemed to be on the mild side effect-wise which is how I'm drawing my conclusions.