Gabapentin

Gabapentin is a prescription anticonvulsant used to treat partial-onset seizures and certain types of neuropathic pain. It is approved for partial seizures in adults (and some pediatric patients) and for postherpetic neuralgia. It is also prescribed off-label for various neuropathic pain conditions and other disorders.

Gabapentin is a structural analogue of gamma-aminobutyric acid (GABA) but does not bind to GABA receptors. Its exact mechanism is not fully understood. It binds to the alpha-2-delta subunit of voltage-gated calcium channels, reducing the release of excitatory neurotransmitters and dampening neuronal excitability. It is not significantly metabolized and is eliminated unchanged by the kidneys.

The medication is taken by mouth, with dose titration to minimize adverse effects. Bioavailability decreases as the dose increases. Absorption may be reduced by certain antacids; it can be taken with or without food. The usual elimination half-life is about 5–7 hours in healthy adults, and doses are adjusted for kidney impairment. Gabapentin enacarbil is a prodrug form approved for extended release, including indications for restless legs syndrome and postherpetic neuralgia.

Common adverse effects include dizziness, somnolence, and peripheral edema; less common effects include fatigue and ataxia. Rare but serious risks include mood changes and suicidality. Abrupt discontinuation can cause withdrawal symptoms and rebound pain, so gradual tapering is recommended. Interactions are limited, although antacids can reduce absorption and concurrent CNS depressants may enhance sedation. Pregnancy and lactation require careful risk–benefit assessment, and dosing often needs adjustment in kidney disease.