Gabapentin Starting Dose for Adults
The recommended starting dose of gabapentin for adults is 300 mg once daily, which can be gradually titrated up to an effective dose range of 900-3600 mg/day in divided doses. 1, 2
Initial Dosing Recommendations
- For adults, gabapentin should be initiated at 300 mg once daily or at bedtime 3, 1
- For postherpetic neuralgia, the FDA-approved approach is to start with 300 mg on day 1, increase to 600 mg/day (300 mg twice daily) on day 2, and 900 mg/day (300 mg three times daily) on day 3 2
- For epilepsy in patients 12 years and older, the starting dose is 300 mg three times a day 2
- Slower titration is recommended for elderly patients or those who are medically frail 3, 1
Titration Schedule
- Dose can be increased by 300 mg increments every 3-7 days as tolerated 1
- Typical titration involves increasing by 300 mg every few days until reaching an effective dose 3
- The maximum time between doses should not exceed 12 hours to maintain therapeutic levels 2
- For neuropathic pain conditions, a target dose of 1800-3600 mg/day divided into three daily doses is often needed for optimal efficacy 4, 5
Dosage Adjustment in Special Populations
- For elderly patients: Start at lower doses and titrate more slowly due to potentially decreased renal function 1, 2
- For patients with renal impairment: Dose adjustment based on creatinine clearance is required 2
- Normal renal function (≥60 mL/min): 300-1200 mg three times daily
- Moderate impairment (30-59 mL/min): 200-700 mg twice daily
- Severe impairment (15-29 mL/min): 200-700 mg once daily
- Very severe impairment (<15 mL/min): 100-300 mg once daily 2
Clinical Considerations
- Gabapentin can be administered with or without food 2
- Therapeutic effects for neuropathic pain may take several weeks to achieve 1
- Common side effects include dizziness, somnolence, peripheral edema, and gait disturbance 5
- Rapid initiation at 900 mg/day has been studied and found to be generally well-tolerated, with only dizziness occurring more frequently compared to slower titration 6
Therapeutic Uses and Dosing
- For neuropathic pain conditions (including postherpetic neuralgia and diabetic neuropathy), doses of 1800-3600 mg/day have shown efficacy 4, 5
- For unexplained chronic cough, a therapeutic trial can begin at 300 mg once daily with dose escalation up to a maximum tolerable daily dose of 1800 mg in two divided doses 3
- For neuropathic corneal pain, gabapentin is considered a third-line agent, initiated at 600 mg once daily and increased every 3 days to a dose of 1800 mg divided in 3 doses 3
Important Considerations
- If discontinuing gabapentin, it should be done gradually over a minimum of 1 week to avoid withdrawal symptoms 2
- Divided doses (typically three times daily) are recommended for optimal therapeutic effect and tolerability 3, 2
- Doses up to 3600 mg/day have been well-tolerated in clinical studies, though additional benefit beyond 1800 mg/day was not consistently demonstrated for postherpetic neuralgia 2, 5