What is the typical dosing regimen for gabapentin (Neurontin) in adults with neuropathic pain or epilepsy?

Gabapentin Dosing for Adults with Neuropathic Pain or Epilepsy

For adults with neuropathic pain, gabapentin should be started at 100-300 mg at bedtime, then gradually increased to 900-3600 mg daily in divided doses (2-3 times daily), with dose adjustments based on pain relief and tolerability. 1, 2

Neuropathic Pain Dosing

Initial Dosing and Titration

• For postherpetic neuralgia, gabapentin should be initiated on Day 1 as a single 300 mg dose, on Day 2 as 600 mg/day (300 mg twice daily), and on Day 3 as 900 mg/day (300 mg three times daily) 2
• Dose increments of 50-100% every few days are recommended until pain relief is achieved 1, 3
• Slower titration is necessary for elderly patients or those who are medically frail 1, 3

Effective Dosage Range

• The effective dosage range for neuropathic pain is 900-3600 mg daily in divided doses 1, 2
• In clinical studies for postherpetic neuralgia, efficacy was demonstrated over a range of doses from 1800 mg/day to 3600 mg/day, though additional benefit of using doses greater than 1800 mg/day was not clearly demonstrated 2
• Doses should be increased until analgesic effect is achieved, side effects become unmanageable, or the conventional maximum dose is reached 3, 1

Administration Schedule

• The total daily dose should be divided into 2-3 administrations per day 1, 2
• The maximum time between doses should not exceed 12 hours 2

Epilepsy Dosing

Adults and Children 12 Years and Older

• Starting dose is 300 mg three times daily 2
• Recommended maintenance dose is 300-600 mg three times daily 2
• Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies 2
• Doses of 3600 mg/day have been administered to a small number of patients for a relatively short duration and were well tolerated 2, 4

Children Ages 3-11 Years

• Starting dose range is 10-15 mg/kg/day, given in three divided doses 2
• Recommended maintenance dose for ages 3-4 years: 40 mg/kg/day in three divided doses 2
• Recommended maintenance dose for ages 5-11 years: 25-35 mg/kg/day in three divided doses 2

Dosage Adjustment in Renal Impairment

• Dose adjustment is required for patients with compromised renal function 1, 2
• For creatinine clearance ≥60 mL/min: 900-3600 mg/day in three divided doses 2
• For creatinine clearance >30-59 mL/min: 400-1400 mg/day in two divided doses 2
• For creatinine clearance >15-29 mL/min: 200-700 mg/day as a single daily dose 2
• For creatinine clearance ≤15 mL/min: 100-300 mg/day as a single daily dose 2
• Patients on hemodialysis require a supplemental post-hemodialysis dose 2

Clinical Considerations

• Patient education should emphasize the trial and error nature of treatment to prevent discouragement 3, 1
• Response to gabapentin may vary among different types of neuropathic pain and individual patients 3, 1
• Gabapentin may be used as a coanalgesic in combination with other pain medications for optimal outcomes 3, 1
• Approximately 35% of patients with neuropathic pain achieve at least 50% pain intensity reduction with gabapentin, compared with 21% for placebo 5, 6
• Common adverse effects include dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (9%) 5, 6
• If gabapentin dose is reduced, discontinued, or substituted with an alternative medication, this should be done gradually over a minimum of 1 week 2

Administration Pearls

• Gabapentin can be administered with or without food 2
• If using scored tablets (600 mg or 800 mg), patients can take half-tablets, but unused halves should be taken as the next dose or discarded if not used within 28 days 2
• Higher doses may require three times daily dosing to maintain therapeutic levels 1