Methods  The clinical usefulness of gabapentin in combination with opioids for Japanese patients with neuropathic cancer pain was assessed in an open-label, single-center, prospective study. Gabapentin was initiated in addition to the drugs currently being administered. The dose of gabapentin was titrated from 200 mg to a maximum dose of 2400 mg per day over 15 days, based on discussion with each patient. The primary endpoint variable was the numerical rating scale (NRS) of 0–10 measured using the brief pain inventory.

Results  From February 2007 to December 2007, gabapentin was administered to 24 patients that were already receiving an opioid without sufficient analgesia. Administration of gabapentin statistically reduced the worst-NRS, the least-NRS, and the average-NRS (7.3 → 5.8, 3.6 → 3.0, 5.8 → 4.5, respectively). Four patients (16.7%) were withdrawn from the study because of adverse events (headache, myoclonus, heartburn, bronchial asthma).

Conclusion  Although gabapentin might be regarded as a promising new adjuvant analgesic for neuropathic cancer pain, our results indicated that the decrease in pain score was of minimal clinical benefit. Controlled trials with other adjuvant analgesics are needed.