Efficacy of tapentadol for first-line opioid-resistant neuropathic pain in Japan.

Background: Cancer-related neuropathic pain is sometimes unresponsive to multidrug treatment. Novel drugs are required to treat such severe pain without necessitating the use of adjuvant analgesics. Tapentadol is a new drug that has a dual mechanism as both an opioid agonist and noradrenalin reuptake inhibitor. The study objective was to investigate the effectiveness of oral tapentadol for relieving cancer-related neuropathic pain.

Methods: A retrospective, single-center, open, non-randomized study was conducted at the Nagoya City University Hospital. The study included 38 Japanese patients with advanced cancer who received opioids, such as tramadol, oral oxycodone and transdermal fentanyl, with or without adjuvant analgesics. Eastern Cooperative Oncology Group performance status, Numerical Rating Scale, primary tumor type, primary opioid and tapentadol doses, adjuvant analgesic prescriptions, outcomes and adverse events of opioid switching were assessed for 7 days.

Results: Eighteen (47.3%) out of 38 patients were enrolled in this study. The average performance status was 2.13 ± 0.94 (mean ± standard deviation). After switching to oral tapentadol, the pain score decreased from 3.78 to 2.78. The patients who had clinically improved effective pain scores had a higher percentage of prior opioid use for more than 2 months. After switching to tapentadol, adverse events were usually mild, with a grade of 1-2 by the Common Terminology Criteria for Adverse Events v4.03.

Conclusions: Tapentadol appears to have an acceptable safety margin and promising efficacy to relieve cancer-related neuropathic pain that is refractory to first-line opioid treatment.