"4 hours to work"? Are you kidding me?
Neurontin works as fast as any other drug. I let a whole 300mg dissolve in my mouth than swallow it. And in about 45 mins I feel most its effects. If you're not feeling neurontin that fast, you have a tolerance, and your just most likely not feeling it at all.
As far as for a coke come down, I would say no don't do it. Although neurontin DOES chill you out, it adds an elusive adrenaline spike that will have you feeling like your on speed... but chill.. but you really just go back and forth.
I think neurtonin could easily exacerbate those effects stimulated effects.