What is the recommended dose of gabapentin (anticonvulsant) for upper limb radicular pain?

Gabapentin Dosing for Upper Limb Radicular Pain

For upper limb radicular pain, gabapentin should be started at 100-300 mg at bedtime or 100-300 mg three times daily, then gradually increased by 100-300 mg every 1-7 days as tolerated, up to a maximum of 3600 mg daily in 3 divided doses. 1, 2

Initial Dosing and Titration

• Start with 100-300 mg at bedtime or 100-300 mg three times daily 1, 2
• Increase dose by 100-300 mg every 1-7 days as tolerated 1, 2
• Dose increments of 50-100% every few days are recommended until pain relief is achieved 1
• Slower titration is advised for elderly patients or those who are medically frail 1, 2

Effective Dosage Range and Administration

• The effective dosage range is 900-3600 mg daily 1, 3
• Total daily dose should be divided into 2-3 administrations per day 1
• Higher doses typically require three times daily dosing to maintain therapeutic levels 1, 2
• An adequate trial of treatment with gabapentin can require 2 months or more 2

Dose Adjustments and Special Considerations

• Increase dose until analgesic effect is achieved, side effects become unmanageable, or maximum dose of 3600 mg/day is reached 1, 2
• Dose adjustment is required for patients with compromised renal function 1, 2
• Gabapentin pharmacokinetics are nonlinear (due to saturable absorption), requiring careful titration 2

Efficacy for Radicular Pain

• Studies show gabapentin is effective for radicular pain, with significant pain reduction observed at doses up to 1800-3600 mg/day 4, 5
• Early treatment with gabapentin shows more rapid reduction of symptoms in radiculopathy 5
• Clinically significant effect was found in 59% of patients with early onset of treatment with gabapentin 5

Monitoring and Side Effects

• Common adverse effects include dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (14%) 3
• Adverse effects are typically mild to moderate and usually subside within approximately 10 days from initiation of treatment 6
• Adverse event withdrawals are more common with gabapentin (11%) than with placebo (8.2%) 3

Clinical Pearls

• Patient education should emphasize the trial and error nature of treatment to prevent discouragement 1, 2
• Response to gabapentin may vary among different types of neuropathic pain and individual patients 1, 2
• Around 3-4 out of 10 patients achieve at least 50% pain relief with gabapentin, compared with 1-2 out of 10 for placebo 3
• Gabapentin may be used as a coanalgesic in combination with other pain medications for optimal outcomes 1, 2

Titration Algorithm

1. Day 1: Start with 300 mg at bedtime 2, 6
2. Day 2-3: Increase to 300 mg twice daily 2, 6
3. Day 4-7: Increase to 300 mg three times daily (900 mg/day) 2, 6
4. Week 2-3: If needed, increase to 600 mg three times daily (1800 mg/day) 2, 6
5. Week 4-8: If needed and tolerated, further increase up to 1200 mg three times daily (3600 mg/day) 2, 3