Rao, R.D., Michalak, J.C., Sloan, J.A., Loprinzi, C.L., Soori, G.S., Nikcevich, D.A., . . . North Central Cancer Treatment Group. (2007). Efficacy of gabapentin in the management of chemotherapy-induced peripheral neuropathy: A phase 3 randomized, double-blind, placebo-controlled, crossover trial (N00C3). Cancer, 110, 2110–2118.

The purpose of the study was to evaluate the effect of gabapentin on chemotherapy-induced peripheral neuropathy (CIPN).

Patients were assigned to either one of two groups: gabapentin followed by placebo or placebo followed by gabapentin. Doses of both capsules were incrementally increased during the course of three weeks to a target does of 2,700 mg. Patients were treated for six weeks and then had a two-week washout period. After the washout period, patients were treated for another six weeks in the crossover. The sample size was determined by power analysis and study measures were obtained weekly.

• The sample consisting of 68 participants with a mean age of 59 years and a range of 25–84 years.
• Women outnumbered men, 73%–27%, respectively.
• Specific diagnoses were not described by the authors, but 50% of the participants were on active treatment at the time of the study.
• All patients had symptom severity of 4 or greater on a numerical rating scale for peripheral neuropathic pain.
• Patients were receiving vinca alkaloids, taxanes, cisplatin-based compounds, or some combination of these.

The study was conducted at multiple outpatient settings in the north-central region of the United States.

• A numeric rating scale of 0-10 for pain.
• The World Health Organization classification scale for neuropathic symptoms (parasthesias, tendon reflexes, weakness, motor loss included).
• The short form McGill pain questionnaire.
• The Brief Pain Inventory.
• A symptom distress scale (five point).
• The Profiles of Mood States.

The McGill pain rating questionnaire at six weeks indicated lower pain in the gabapentin-treated groups. No other differences were noted between groups at any point in time during the study. On the numerical scale, a slight reduction in pain was seen in all participants. Improvement was highest in patients who had higher baseline average pain and in those currently in active chemotherapy treatment.  Most frequent adverse events were dizziness and fatigue and no differences in adverse events were noted based on gabapentin treatment.

The findings failed to demonstrate any benefit in using gabapentin for CIPN.

• Limitations included a sample size of less than 100 participants.
• A 41% dropout rate occurred, which was not discussed.
• Because of the dropouts, the sample size in the final analysis was underpowered.
• No intention-to-treat analysis was reported and no mention was made of other medications used to treat pain.

The findings do not support the use of gabapentin for the management of CINV.