Gabtin Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of Action: Gabapentin is structurally related to GABA. However, it does not bind to GABA_A or GABA_B receptors, and it does not appear to influence synthesis or uptake of GABA. The exact mechanism of action of gabapentin is unknown and remains to be established. High affinity gabapentin binding sites have been found to be located throughout the brain; these sites correspond to presence of voltage-gated calcium ion channels specifically possessing the alpha-2-delta-1 subunit. This channel appears to be located presynaptically, and may modulate the release of excitatory neurotransmitters which participate in epileptogenesis and nociception.
Pharmacokinetics: Absorption: Gabapentin is absorbed from the gastrointestinal tract by means of a saturable mechanism.
Gabapentin bioavailability is not dose-proportional. As the dose is increased, bioavailability decreases.
After multiple dosing peak plasma concentrations are usually achieved within 2 to 3 hours of a dose and steady state achieved within 1 to 2 days.
Distribution: Gabapentin is widely distributed throughout the body but binding to plasma proteins is minimal (<3%).
Gabapentin is actively transported and the placenta and distributed into breast milk.
Metabolism: Gabapentin is not appreciably metabolized.
Excretion: Most of a dose is excreted unchanged in the urine with the remainder appearing in the faces. The elimination half-life is 5 to 7 hours.