Gabapentin as an adjuvant to opioid analgesia for neuropathic cancer pain.

Gabapentin was administered as an "add on" therapy to 22 patients with neuropathic cancer pain only partially responsive to opioid therapy. Global pain, burning pain, shooting pain episodes, and allodynia were assessed separately. Gabapentin was given for at least a week and efficacy was assessed after 7 to 14 days of therapy. Global pain score decreased from a mean (+/- SD) of 6.4 (+/- 1.5) to 3.2 (+/- 1.3) (95% confidence interval of the baseline minus final score differences [95% CI] = 1.0-2.4). Burning pain intensity decreased from a mean (+/- SD) of 5.1 (+/- 3.6) to 2.0 (+/- 2.3) (95% CI = 1.5-3.8), and episodes of shooting pain decreased in frequency from 7.2 (+/- 3.7) to 2.2 (+/- 2.2) daily episodes (95% CI = 1.8-4.3). Allodynia was found in 9 patients and disappeared in 7 during gabapentin administration. Twenty patients judged the new drug efficacious in relieving their symptoms. The potential role of gabapentin as an adjuvant to opioid analgesia in cancer pain is discussed.