Gabapentin (Neurontin) is not a GABA anolog. It works on the calcium and sodium channels. As aforementioned, they created it as a GABA analog, I believe in the 60's. Ironically, it has zero affinity for any GABA receptors.
I have 8 years of recreational gabapentin use, and think of myself as a well knowledged person when it comes to this chemical. There are some things that gabapentin will NOT work with. I have found that if you smoke a bunch, or especially eat any THC, your gabapentin will not work. Some herbs also completely block the chemistry.
Kava is an herb that is quite unique with regards to gabapentin, as well as alcohol. With gabapentin, if taken together, it creates an almost antisocial and mega mellowed out experience. Not awesome, IMO. However, if you take kava a minimum of 9 hours BEFORE a Gabapentin dose during a gabapentin binge, it stops tolerance increase. With consistent kava use, your gabapentin AND alcohol tolerance will drop. The reason being, is kava has a reverse tolerance. And since it plays on calcium channels, as well as GABA receptors, it reverses both tolerances.
As for drug interactions, here is what I've found: MDMA and gabapentin cause black outs. Gabapentin mixed with LSD can negate nausea. Gabapentin and opiates/oids, gabapentin effects are increased, and opiate slightly decreased. Gabapentin and alcohol is a strange one. If you drink to the point of a buzz before taking gabapentin, the gabapentin will not work. I haven't figured out why yet. And no, it's not because of GABA activity. Gabapentin before weed is great, but too much weed/THC before the gabapentin, leads to the 'pentin not working hardly at all, no matter the dose. Gabapentin and cocaine... Well, it's cocaine. So, once the cocaine enters your system, the gabapentin completely disappears.
The more you know. Most of this can be verified though PubMed. Also, any questions, PM me. I used to love my cocktails, and have ridiculous experiences with various combinations. Be safe.