They actually found gabapentine has minimal effects on gaba receptors, it appears to work as a calcium channel blocker, Pharmacology Gabapentin was initially synthesized to mimic the chemical structure of the neurotransmitter gamma-aminobutyric acid (GABA), but is not believed to act on the same brain receptors. The mechanism of action that leads to its rapid analgesic effect is simply unknown. Some of its activity may involve interaction with voltage-gated calcium channels. Gabapentin binds to the ?2? subunit (1 and 2) and has been found to reduce calcium currents after chronic but not acute application via an effect on trafficking of voltage-dependent calcium channels in the central nervous system. Another possible mechanism of action, reported by Ben Barres and colleagues in Cell in 2009, is that gabapentin halts the formation of new synapses. http://en.wikipedia.org/wiki/Gabapentine If gabapentine helps it might be worth looking into other calcium channel blockers. alpha 2 adrenergic agonists like tizanidine and clonidine might also be helpful for those who have anxiety, insomnia etc etc and also been used in POTS cheers!!!