Fast Fact and Concept #049: Gabapentin for Neuropathic Pain

2nd Edition

Author(s): Anita Kishore, Linda King, MD and David E. Weissman, MD

Gabapentin (Neurontin) is widely used for neuropathic pain. Controlled clinical trials in diabetic neuropathy and postherpetic neuralgia show that gabapentin at 2400-3600 mg/day has an efficacy similar to the tricyclic antidepressants and carbamazepine. Consistent, though less compelling clinical evidence supports its use for cancer pain, pain associated with HIV infection, chronic back pain and others (readers wanting more in depth research findings are urged to view the 2005 report in the Cochrane Database; see reference below). The exact mechanism and site of action of gabapentin is unknown. Gabapentin is generally well-tolerated, easily titrated, has few drug interactions, and does not require laboratory monitoring. However, cost may be a limiting factor for some patients. Patients suitable for Neurontin should have a clear neuropathic pain syndrome, characterized by sharp, shooting, lancinating and/or burning pain, in a nerve root (radicular) or stocking/glove distribution.

Adult Dosing

Gabapentin is started at low doses (100 mg qD to 100 mg TID) and increased by 100 – 300 mg every 1-3 days to effect (a typical schedule might include: Day 1: 300 qhs; Day 3: 300 mg BID; Day 5: 600 mg BID, Day 7: 600 mg TID). The usual effective total daily dose is 900-3600 mg, administered in three divided doses per day; higher doses may be needed. Titration should proceed more slowly in elderly patients.

Dosing in Renal Failure

Gabapentin doses must be reduced for patients with renal insufficiency.

• CrCl (Creat. Clear.) 30-60: max dose 300 mg PO bid;
• CrCl 15-30: max dose 300 mg PO qd;
• CrCl < 15: max 300 mg PO qod. For patients on hemodialysis: max 200-300mg dose only after each dialysis session.

Adverse Reactions

Sedation and confusion, as well as dizziness and ataxia, are the most common side effects, especially with rapid dose titration. Tolerance to these effects appears to develop within a few days if the dose is held at the highest tolerated dose until symptoms improve or stabilize.

Dosage Formulations

Neurontin is available in 100 mg, 300 mg, and 400 mg capsules, 600 mg and 800 mg tablets, and as a liquid (250mg/5mL).

Cost

Neurontin is more expensive than older agents used for neuropathic pain (tricyclic antidepressants and older anti-epileptic drugs such as carbamazepine).

Summary

Gabapentin is a safe and effective adjuvant analgesic for neuropathic pain. Physicians should become comfortable using and titrating gabapentin in patients with neuropathic pain syndromes.

References

1. Anticonvulsant drugs for acute and chronic pain. The Cochrane Database of Systematic reviews. May, 2005. http://www.cochrane.org/reviews/en/ab001133.html
2. Adapted from: Emanuel, LL, von Gunten, CF, Ferris, FF (eds.). Module 4: Pain Management. The EPEC Curriculum: Education for Physicians on End-of-life Care. www.EPEC.net: The EPEC Project, 1999.
3. Caraceni A, et al. Gabapentin for neuropathic cancer pain: a randomized controlled trial from the Gabapentin cancer pain study group. J Clin Onc 2004;22:2909-2917.

Fast Facts were edited by David Weissman MD, Palliative Care Center, Medical College of Wisconsin until January 2007.  For comments/questions write to the current editor, Drew Rosielle MD: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu

Copyright/Referencing Information : Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing. Kishore A and King L. Gapapentin for neuropathic pain. Fast Fact and Concept #49 2nd Edition August 2005. End-of-Life Palliative Education Resource Center www.eperc.mcw.edu.

Creation Date: 9/2001; 2nd Edition August 2005.

Purpose: Instructional Aid, Self-Study Guide, Teaching

Audience(s)

ACGME Competencies: Medical Knowledge

Keyword(s): Pain>non-opioids