Gabapentin

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General

  • Type: Anticonvulsants; GABA analog
  • Dosage Forms: capsule, tablet, oral solution 250mg/5mL
  • Common Trade Names: Neurontin, Gralise

Adult Dosing

Partial Seizures

  • Adjunctive therapy for partial seizures with or without secondary generalization
  • Initial: 300mg PO q8hr
  • May increase up to 600mg PO q8hr

Post herpetic neuralgia

  • Day 1: 300mg PO qDay
  • Day 2: 300mg PO q12hr
  • Day 3: 300mg PO q8hr

Muscle Cramps (Off-label)

  • 100-300mg PO qHS; may titrate to 300-400mg q8hr PRN

Anxiety (Off-label)

  • 300mg PO qHS initially, THEN 300mg PO q8h; may further increase as tolerated

Diabetic Neuropthy (Off-label)

  • 900mg/day PO initially; may increase gradually q3Days to 1800-3600mg/day

Neuropathic Pain

  • 600mg PO load in ED
  • Discharge with 300mg → 900mg per day divided tid (as in post-herpetic neuralgia regimen)
  • Discharge with pain specialist follow-up
  • Max dosage 3600mg if patient already on gabapentin
  • Taper dose > 7 days to discontinue[1]

Pediatric Dosing

Partial seizures

Adjunct for partial seizures with out secondary generalization in patients> 12yo with epilepsy; also adjunctive therapy for partial seizures in patients 3-12 years

  • <3 years: Safety and efficacy not established
  • 3-12 years (initial dose): 10-15mg/kg/day PO divided q8hr initially; titrate up in 3d to effective maintenance dose
  • 3-4 years (maintenance): 40mg/kg/day PO divided q8hr
  • 5-12 years (maintenance): 25-35mg/kg/day PO divided q8hr
  • >12 years (initial dose): 300mg PO q8h; may increase up to 600mg PO q8h

Special Populations

  • Pregnancy Rating: C
  • Lactation: Enters breast milk; use with caution
  • Renal Dosing
CrCl>60 mL/min: 300-1200mg PO TID
CrCl 30-60 mL/min: 200-700mg q12hr
CrCl 15-29 mL/min: 200-700mg qDay
CrCl<15 mL/min: 100-300mg qDay
HD: 125-350mg posthemodialysis after each 4h dialysis interval
  • Hepatic Dosing
    • Adult: no modifications
    • Pediatric: no modifications

Contraindications

  • Allergy to class/drug

Adverse Reactions

Serious

  • Depression/suicidality
  • SJS
  • anaphylaxis
  • angioedema

Common

  • >10% ataxia, dizziness, fatigue, somnolence
  • 1-10% diplopia, nystagmus, tremor, amblyopia, back pain, constipation, depression, dry mouth, dysarthria, dyspepsia, increased appetitie, leukopenia, myalgia, nervousness, peripheral edema, pharyngitis, puritis, rhinitis, vasodilation, weight gain

Pharmacology

  • Half-life: 5-7hr
  • Metabolism: not metabolized
  • Excretion: Renal
  • Mechanism of Action: GABA analogue, but has no effect on GABA binding, uptake or degradation; mech for analgesic and anticonvulsant activity unknown

See Also

References

  1. Epocrates. Gabapentin Monograph. https://online.epocrates.com/u/10a1022