Brain cells need to work (fire) at a certain rate to function normally. During a seizure, brain cells are forced to work much more rapidly than normal. Gabapentin helps prevent brain cells from working as fast as a seizure requires them to. In this way, seizures can be stopped when they are just beginning.

It is not fully known how gabapentin affects the brain to stop seizures. The current theory is that gabapentin causes brain cells to make more GABA, the major inhibitory neurotransmitter in the brain. When GABA is transmitted from one brain cell to another, the second brain cell is less likely to fire and be part of a seizure.