Gabapentin is structurally related to GABA. However, it does not bind to GABAA or GABAB receptors, and it does not appear to influence synthesis or uptake of GABA.
High affinity gabapentin binding sites have been located throughout the brain; these sites correspond to the presence of voltage-gated calcium 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.
Variable, from proximal small bowel by L-amino transport system; saturable process; dose-dependent
Vd: 58 ± 6 L; CSF concentrations are ~20% of plasma concentrations
Proportional to renal function; urine (as unchanged drug)
Clearance: Apparent oral clearance is directly proportional to CrCl: Clearance in infants is highly variable; oral clearance (per kg) in children <5 years of age is higher than in children ≥5 years of age
Time to Peak
Immediate release: Infants 1 month to Children 12 years: 2 to 3 hours; Adults: 2 to 4 hours; Extended release: 8 hours
Infants 1 month to Children 12 years: 4.7 hours
Adults, normal: 5 to 7 hours; increased half-life with decreased renal function; anuric adult patients: 132 hours; adults during hemodialysis: 3.8 hours