TaperCommunitygabapentin
Boxed Warning
Respiratory depression risk when used with CNS depressants, particularly opioids. Increased risk of suicidal thoughts and behavior (anticonvulsant class warning).
Gabapentin is an anticonvulsant approved for epilepsy (adjunctive therapy for partial seizures) and postherpetic neuralgia. It is widely prescribed off-label for neuropathic pain, anxiety, insomnia, and alcohol/benzodiazepine withdrawal. Despite its name, it does not bind GABA receptors.
100mg, 300mg, 600mg, 800mg
Capsules: 100mg, 300mg, 400mg; Tablets: 600mg, 800mg; Oral solution: 250mg/5mL; Extended-release tablets (Gralise): 300mg, 600mg
Category C (risk cannot be ruled out)
Binds to the alpha-2-delta subunit of voltage-gated calcium channels, reducing calcium influx and subsequent release of excitatory neurotransmitters (glutamate, norepinephrine, substance P). Does not bind GABA receptors or affect GABA uptake/metabolism.
Short half-life with non-linear absorption. Multiple daily doses needed. Water titration method works well for precise reductions.
Reduce by no more than 10% per step. Non-linear pharmacokinetics mean absorption decreases at higher doses. Capsules can be opened for water titration.
Toxicity
Relatively low acute toxicity. Respiratory depression when combined with opioids or CNS depressants. Suicidal ideation (class warning for anticonvulsants). Physical dependence with chronic high-dose use.
Pharmacokinetics
Absorbed via L-amino acid transport system in the small intestine. Bioavailability is dose-dependent (inversely proportional): ~60% at 300mg, ~35% at 1600mg. Tmax 2–3 hours. Food modestly increases absorption.
~0.8 L/kg (58 L in 72 kg individual)
Not appreciably metabolized in humans. No CYP involvement. Excreted unchanged.
Renal (~100% excreted unchanged). Clearance is proportional to creatinine clearance.
<3% (not significantly protein bound)
~120–130 mL/min (renal clearance, similar to GFR)
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