Gabapentin Dosing and Frequency for Adults
The typical starting dose of gabapentin for adults is 100-300 mg at bedtime or 100-300 mg three times daily, with gradual titration based on response and tolerability. 1, 2
Initial Dosing Protocol
- Starting dose: 100-300 mg at bedtime or 100-300 mg three times daily 1, 2
- Titration schedule:
- Day 1: 300 mg once daily
- Day 2: 300 mg twice daily (600 mg/day)
- Day 3: 300 mg three times daily (900 mg/day) 2
- Dose increases: Can be titrated up by 50-100% every few days as needed and tolerated 3
Target Therapeutic Dosing
- Typical effective dose range: 1800-3600 mg/day in divided doses 1, 2
- Maximum recommended dose: 3600 mg/day in three divided doses 2
- Dosing frequency: Three times daily (TID) is standard; maximum time between doses should not exceed 12 hours 2
Dosing Considerations for Special Populations
Renal Impairment
Dose adjustment is required based on creatinine clearance:
- CrCl ≥60 mL/min: 900-3600 mg/day (300-1200 mg TID)
- CrCl 30-59 mL/min: 400-1400 mg/day (200-700 mg BID)
- CrCl 15-29 mL/min: 200-700 mg/day (200-700 mg once daily)
- CrCl <15 mL/min: 100-300 mg/day (100-300 mg once daily) 2
Elderly Patients
- Lower starting doses and slower titration are recommended due to potential decreased renal function 1, 2
- Start at the lower end of the dosing range (100 mg at bedtime) and titrate more gradually 1
Clinical Pearls and Pitfalls
- Bioavailability: Gabapentin has dose-dependent absorption that becomes saturated at higher doses, potentially limiting effectiveness of very high doses 4
- Timing of doses: At doses of 3600 mg/day, three times daily dosing is adequate; however, at 4800 mg/day, four times daily dosing may improve bioavailability by 22% 4
- Duration of trial: An adequate trial of gabapentin may require 2 months or more to determine effectiveness 1
- Administration: Can be taken with or without food 2
- Common adverse effects: Dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (14%) 5
- Monitoring: Follow-up within 2-4 weeks to evaluate efficacy and side effects is recommended 1
Indication-Specific Dosing
For neuropathic pain conditions:
- Postherpetic neuralgia: Effective doses range from 1800-3600 mg/day 2, 5
- Diabetic neuropathy: Effective doses typically range from 1800-3600 mg/day 5
- Unexplained chronic cough: Target dose of 1800 mg/day (in two divided doses) 3
- Alcohol use disorder: Target dose of 1800 mg/day 1
Gabapentin's effectiveness for pain relief is dose-dependent, with higher doses generally providing better pain control. At doses of 1800-3600 mg/day, approximately 30-40% of patients with neuropathic pain will achieve at least 50% pain reduction compared to 17-21% with placebo 5.