Gabapentin Dosing and Treatment Plan
Gabapentin should be initiated at 300 mg on day 1,600 mg/day (300 mg twice daily) on day 2, and 900 mg/day (300 mg three times daily) on day 3, with subsequent titration to an effective dose of 1800 mg/day, as doses above this show minimal additional benefit with significantly higher risk of adverse effects. 1, 2
Initial Dosing and Titration
- Starting dose: 300 mg at bedtime on day 1,300 mg twice daily on day 2,300 mg three times daily on day 3 1, 2
- Titration rate: Increase by 300 mg every 1-7 days as tolerated 1
- Target therapeutic dose: 900-1800 mg/day (most effective dose range with lower risk of adverse effects) 1
- Maximum dose: 3600 mg/day, though doses above 1800 mg/day have diminishing returns and increased side effects 1, 2
- Elderly patients: Require slower titration and dose adjustment based on creatinine clearance 1, 2
Dosage by Indication
Postherpetic Neuralgia
- Initial titration as above
- Effective dose range: 1800-3600 mg/day
- Clinical studies showed comparable efficacy across this range, with no additional benefit demonstrated above 1800 mg/day 2
Epilepsy with Partial Onset Seizures
- Adults and children ≥12 years: 300-600 mg three times daily (900-1800 mg/day)
- Children 5-11 years: 25-35 mg/kg/day in three divided doses
- Children 3-4 years: 40 mg/kg/day in three divided doses 2
Renal Dose Adjustment
| Creatinine Clearance (mL/min) | Total Daily Dose Range (mg/day) | Dose Regimen |
|---|---|---|
| ≥60 | 900-3600 | 300-1200 mg TID |
| >30-59 | 400-1400 | 200-700 mg BID |
| >15-29 | 200-700 | 200-700 mg QD |
| ≤15 | 100-300 | 100-300 mg QD |
For patients on hemodialysis: Administer maintenance dose based on creatinine clearance plus supplemental post-hemodialysis dose after each 4-hour session 1, 2
Duration of Trial and Efficacy Assessment
- Titration period: 3-8 weeks
- Assessment period: 2 weeks at maximum tolerated dose
- Total trial duration: 5-10 weeks before determining treatment failure 1
- Efficacy evaluation: Assess pain relief, functional improvement, and adverse effects at each dose increase 1
Discontinuation Protocol
- Never discontinue abruptly - taper gradually over at least 1 week
- Recommended tapering schedule:
- Reduce to 300 mg at bedtime for 1-3 days
- Then 300 mg twice daily for 1-3 days
- Then 300 mg three times daily before stopping 1
Common Adverse Effects and Monitoring
- Most common adverse effects: Dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (14%) 1, 3
- Monitoring: Assess for adverse effects at each dose increase
- Renal function: Monitor regularly, especially in elderly patients 1
- Risk of falls: Higher risk with doses above 1800 mg/day 1
Key Clinical Considerations
- Dose optimization: The 900-1800 mg/day range is effective for most patients with lower risk of adverse effects 1
- Common prescribing errors:
- Underdosing (prescribing doses lower than those used in clinical trials)
- Overly rapid titration (increases side effects)
- Failure to adjust for renal impairment
- Abrupt discontinuation (causes withdrawal symptoms) 1
- Administration: Can be taken with or without food 2
- Divided tablets: If a scored 600 mg or 800 mg tablet is divided, the unused half-tablet should be taken as the next dose and discarded if not used within 28 days 2
Efficacy in Neuropathic Pain Conditions
- Postherpetic neuralgia: 34% of patients achieve at least 50% pain reduction (vs 21% with placebo) 3
- Diabetic neuropathy: 38% of patients achieve at least 50% pain reduction (vs 21% with placebo) 3
- Other neuropathic pain conditions: Limited evidence, but may be effective for some patients 3, 4
Remember that approximately half of patients treated with gabapentin will not achieve worthwhile pain relief but may still experience adverse effects 3, 4.