Gabapentin
Common Brand Names: Neurontin, Gralise
Generic Available*
Common Dosage Forms:
Capsules*: 100 mg, 300 mg, 400 mg
Tablets*: 600 mg, 800 mg
Tablets, extended-release (Gralise): 300 mg, 600 mg
Oral Solution*: 250 mg/5 mL (store refrigerated)
FDA Indications/Dosages:
As adjunctive therapy in the treatment of partial seizures with and without secondary generalization in adults with epilepsy: Start with 300 mg at bedtime on day 1. Increase to 300 mg twice a day on day 2 and 300 mg three times a day on 3 day. The effective dose is 900 mg to 1800 mg per day given in three divided doses. Doses of 2400 mg per day have been tolerated by patients. If gabapentin is discontinued, a graduated dose reduction should be done over a period of one week.
Adult dosage adjustment when creatinine clearance (CrC): >60 mL/min: 400 mg three times a day.
Adult dosage adjustment when CrC=300 mg two times a day.
Adult dosage adjustment when CrC <15 mL/min: every other day.
As adjunctive therapy in the treatment of partial seizures in pediatric patients age 3-12 years: Start with 10-15 mg/kg/day in 3 divided doses. Titrate up to 25-35 mg/kg/day for patients ≥5 years and up to 40 mg/kg/day for patients 3-4 years.
Treatment of postherpetic neuralgia in adults: Start with 300 mg on day one, 300 mg twice a day on day two, and 300 mg three times a day on day three. The dose can be titrated up to 600 mg given three times a day (1800 mg/day).
Pharmacology/Pharmacokinetics: The exact mechanism of action of gabapentin is unknown. It exhibits anti-seizure activity in mice and rats in both the maximal electroshock and pentylenetetrazole seizure models and other preclinical models. Gabapentin is structurally related to the neurotransmitter GABA (gamma-aminobutyric acid) but it does not interact with GABA receptors and it is not an inhibitor of GABA uptake or degradation. Elimination half-life after an oral dose is 5-7 hours. Excretion occurs by the renal route as unchanged drug.
Drug Interactions: Antacids decrease bioavailability when given at the same time as gabapentin,
Contraindications/Precautions: Antiepileptic drug should not be discontinued abruptly due to a possibility of precipitating seizures. The safety and efficacy in pediatric patients below the age of 12 years have not been established. Use caution in patients with renal impairment (see Dosage Ranges). Pregnancy Category C.
Adverse Effects: The most common adverse effects are somnolence (19%), dizziness (17%), ataxia (12%), fatigue (11%), nystagmus (8%), tremor (7%), diplopia (6%), rhinitis and blurred vision (4%). Uncommon but rare adverse effects include elevate creatine kinase and rhabdomyolysis.
Patient Consultation:
May cause drowsiness. Use caution while operating machinery or when mental alertness is required.
Avoid alcohol while taking this medication.
Do not abruptly discontinue therapy, dose should be tapered over a one week period.
May be taken without regard to meals.
Store in a cool, dry place away from sunlight and children.
Contact a physician if the above side effects are severe or persistent.
If a dose is missed, take it as soon as possible. Do not double doses.
