Do you have any experience with gabapentin? I am prescribed 2400mg/day (split into 4 doses) and have many times taken it all at once. However, I've been scripted gabapentin for a ~3 years now.
I will say that my first time attempting a recreational dose of gabapentin, with very little prior experience and no tolerance, 1200mg left me crazy chatty, somewhat drunk-ish feeling, and produced a definite hangover the following day, including what I assume was some rebound depression.
I can't say that I recommend gabapentin as a recreational drug.