Tramadol/Acetaminophen Combination Tablets in Cancer Patients with Chemotherapy-Induced Peripheral Neuropathy: A...

Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent complication in patients receiving anticancer chemotherapy, but no effective treatment is yet available. To evaluate the efficacy and safety of a tramadol/acetaminophen combination tablets for CIPN. This is a single-arm phase II study of tramadol/acetaminophen. Eligible patients had received oxaliplatin, paclitaxel, or nab-paclitaxel, and were experiencing CIPN. The patients were given one tablet (37.5 mg tramadol plus 325 mg acetaminophen) twice a day for 7 days, then four times a day for 21 days. The primary endpoint was the numerical rating scale of neuropathic pain. Other endpoints included the potential of CYP2D6 genetic variants to effective response or toxicity. Of the 34 patients enrolled, 23 completed the protocol treatment. The mean neuropathic pain score decreased insignificantly from 5.53 at baseline to 5.00 at 28 days (95% confidence interval -0.21 to 1.43; p = 0.139). However, 13 of the 23 (56.5%) patients who completed the protocol treatment showed improvement of the neuropathic pain score by at least 1 point. No severe adverse events were observed. Tramadol/acetaminophen may be more effective in patients with the intermediate metabolizer phenotype of the CYP2D6 single nucleotide polymorphisms (SNPs) although at the cost of increased toxicity. Although tramadol/acetaminophen tablets did not reduce neuropathic pain to a statistically significant degree, the neuropathic pain severity reduced in more than a half of the patients.