Cross-tolerance is near complete. I speak purely from experience Sonic my man. Gabapentinoids have seemed to proliferate at a fucking pandemic rate over the past ten years. This isn't such a bad thing (right?) considering they seem to be both quite helpful and relatively safe, even in exponentially extreme dosages. Track down pubmed for at least one reference regarding what would be considered a massive overdose of Pregabalin (Lyrica) with mild, non-life threatening symptoms resolving within several hours.
I'm of the opinion that they are all essentially different forms of delivery for the same drug with the primary differentiating factors being their efficiency.
It's worth noting that in extremely high dosages, a small segment of the population will experience tics, uncontrolled motor activity and such, which can be mitigated by either sitting or laying. Said convulsive activity appears to be completely non-epileptic and also resolves within several hours.
