The mechanism of action of carbamazepine and its derivatives is relatively well understood.[medical citation needed] Carbamazepine is a use-dependant blocker of voltage-gated sodium channels. It is ionised within intracellular fluid, and is then able to bind to activated voltage-gated sodium channels, preventing repetitive and sustained firing of an action potential.This leaves the affected cells less excitable until the drug dissociates. Carbamazepine is also a GABA receptor agonist, as it has also been shown to potentiate GABA receptors made up of alpha1, beta2, and gamma2 subunits.[26] This mechanism may contribute to its efficacy in neuropathic pain and bipolar disorder. Laboratory research has further demonstrated that carbamazepine is a serotonin releasing agent and possibly even a serotonin reuptake inhibitor.