What is the recommended dose of gabapentin (Gabapentin) for diabetic (DM) neuropathy?

Gabapentin Dosing for Diabetic Neuropathy

Start gabapentin at 300 mg once daily at bedtime on day 1, increase to 600 mg divided in 2-3 doses on day 2, then titrate by 100-300 mg every 1-7 days as tolerated to reach a target dose of 1800-3600 mg daily divided into three doses. 1

Initial Dosing Strategy

• Begin with 100-300 mg at bedtime or 100-300 mg three times daily 1, 2
• A practical titration schedule is:
  • Day 1: 300 mg once daily 1
  • Day 2: 600 mg divided in 2-3 doses 1
  • Days 3-14: Increase by 100-300 mg every 1-7 days based on tolerability 1, 2

Target Therapeutic Dose

• The effective analgesic dose range is 1800-3600 mg per day divided into three doses 1, 2, 3
• Treatment should start at 900 mg/day (300 mg three times daily) and titrate to 1800 mg/day for greater efficacy, with doses up to 3600 mg/day needed in some patients 4
• In painful diabetic neuropathy specifically, 38% of patients achieve substantial benefit (≥50% pain relief) at doses of 1200 mg daily or greater, compared to 21% with placebo (NNT 5.9) 3

Efficacy Assessment Timeline

• Evaluate pain reduction after 2-4 weeks of therapy 1, 2
• Consider treatment successful if pain is reduced by ≥30% from baseline 1, 2
• Allow 3-8 weeks for titration plus 2 weeks at maximum dose to properly evaluate efficacy 1
• An adequate trial may require 2 months or more 1, 2
• If inadequate response after 4 weeks at maximum tolerated dose, switch to an alternative agent 1

Special Populations and Dose Adjustments

• Elderly patients: Start with lower doses (100 mg at bedtime) and use slower titration due to increased risk of sedation, dizziness, and cognitive effects 1
• Renal impairment: Reduce dose in patients with impaired renal function 1, 2

Common Pitfalls to Avoid

• Do not undertitrate: Many patients require 1800-3600 mg/day for adequate pain relief; stopping at lower doses (900-1200 mg/day) is a common reason for treatment failure 4
• Do not discontinue prematurely: Allow at least 2 months for full therapeutic trial before declaring treatment failure 1, 2
• Monitor for peripheral edema (7% incidence), gait disturbance (14%), dizziness (19%), and somnolence (14%) 2, 3

Alternative Agents if Gabapentin Fails

• Pregabalin: Start at 50 mg three times daily or 75 mg twice daily, maximum 600 mg/day (NNT 4.04 for 600 mg/day in diabetic neuropathy) 1, 5, 3
• Duloxetine: 60-120 mg/day (NNT 5.2 for 60 mg/day, NNT 4.9 for 120 mg/day) 1, 2
• Tricyclic antidepressants: Start at 10 mg/day, increase to 75 mg/day (NNT 1.5-3.5), but use cautiously in cardiovascular disease 1, 2

Critical Context

• Optimal glycemic control must be the first step in managing diabetic neuropathy 2
• Pharmacologic treatments are symptomatic only and do not modify disease progression 2