Gabapentin comes as:
- 100 mg, 300 mg, and 400 mg capsules
- 300 mg, 600 mg, and 800 mg tablets
- a 250 mg/5 mL oral (by mouth) solution.
Inactive ingredients in the capsules include lactose, cornstarch, and talc.
- The 100-mg capsule shell also contains: gelatin and titanium dioxide.
- The 300-mg capsule shell also contains: gelatin, titanium dioxide, and yellow iron oxide.
- The 400-mg capsule shell also contains: gelatin, red iron oxide, titanium dioxide, and yellow iron oxide. The imprinting ink contains FD&C Blue No. 2 and titanium dioxide.
Inactive ingredients in the tablets include poloxamer 407, copolyvidonum, cornstarch, magnesium stearate, hydroxypropyl cellulose, talc, candelilla wax, and purified water.
Inactive ingredients in the oral solution include glycerin, xylitol, purified water, and artificial flavor
Usual Adult Dose for Epilepsy:
Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.
The safety and effectiveness of gabapentin available under the trade name Gralise (R) or Horizant (R) in patients with epilepsy has not been studied.
Usual Adult Dose for Postherpetic Neuralgia:
Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
The dose may be titrated up as needed for pain relief to a daily dose of 1800 mg.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses.
Efficacy was demonstrated in clinical studies over a range of 1800 mg/day to 3600 mg/day. However, no additional benefit was demonstrated from the use of doses over 1800 mg/day.
Gabapentin available under the trade name Gralise (R):
Maintenance dose: Gralise (R) should be titrated to 1800 mg orally once daily with the evening meal.
Recommended titration schedule:
Day 1: 300 mg orally with the evening meal
Day 2: 600 mg orally with the evening meal
Days 3 through 6: 900 mg orally with the evening meal
Days 7 through 10: 1200 mg orally with the evening meal
Days 11 through 14: 1500 mg orally with the evening meal
Day 15: 1800 mg orally with the evening meal
Gralise (R) is not interchangeable with other gabapentin products because of differing pharmacokinetic profiles that affect the frequency of administration.
Gabapentin enacarbil extended release tablets available under the trade name Horizant (R):
The recommended dosage is 600 mg orally twice daily. Therapy should be initiated at a dose of 600 mg orally in the morning for 3 days of therapy, then increased to 600 mg twice daily (1,200 mg/day) on day four.
Gabapentin enacarbil extended release tablets available under the trade name Horizant (R) and gabapentin are not interchangeable.
Usual Adult Dose for Restless Legs Syndrome:
Gabapentin enacarbil available under the trade name Horizant (R):
600 mg orally once daily with food at about 5 PM
Usual Pediatric Dose for Epilepsy:
Less than 3 years: Effectiveness has not been established.
Greater than or equal to 3 and less than 12 years:
Starting Dose: ranges from 10 to 15 mg/kg/day in 3 divided doses.
Effective Dose: reached by upward titration over a period of approximately 3 days. The effective dose of gabapentin in patients 5 years of age and older is 25 to 35 mg/kg/day and given in divided doses (three times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (three times a day). Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well tolerated in a long term clinical study. The maximum time interval between doses should not exceed 12 hours.
Greater than 12 years:
Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.
Dose Adjustments
Because elderly patients are more likely to have decreased renal function, the dose of this drug should be adjusted based on CrCl values.
GRALISE (R):
-If the dose of this drug under the trade name Gralise (R) is reduced, discontinued, or substituted with an alternative medication, this should be done gradually over a minimum of 1 week or longer or as directed by the physician.
HORIZANT (R):
-If the dose of this drug available under the trade name Horizant (R) is discontinued, patients with RLS receiving 600 mg or less once daily can discontinue the drug without tapering. If the recommended dose is exceeded, the dose should be reduced to 600 mg daily for 1 week prior to discontinuation to minimize the potential of withdrawal seizure.
-Patients with PHN receiving Horizant (R) twice daily should reduce the dose to once daily for 1 week prior to discontinuation to minimize the potential for withdrawal seizure.
Precautions
-Safety and efficacy have not been established in patients younger than 18 years in the management of postherpetic neuralgia.
-Safety and efficacy have not been established in patients younger than 3 years in the adjunctive treatment of partial seizures.
-Safety and efficacy have not been established in patients younger than 18 years for gabapentin available under the trade names Gralise (R) or Horizant (R).
Consult WARNINGS section for additional precautions.