Adhesive capsaicin 8% patch for improved control of pain caused by chemotherapy-induced peripheral neuropathy in patients with multiple myeloma: A single-centre, seven-case series

Background Capsaicin is a highly selective agonist of the transient receptor potential vanilloid 1. The adhesive capsaicin patch provides a high capsaicin concentration (8%) directly in the painful area – its efficacy in benign peripheral neuropathic pain (diabetic neuropathy or postherpetic neuralgia) has recently been described in the literature. However, there is scant evidence of its efficacy in chemotherapy-induced peripheral neuropathy (CIPN). This is a concern for patients with multiple myeloma, who suffer from peripheral neuropathic pain induced by first-line treatments (bortezomib or thalidomide). Aim To describe improved control of CIPN in patients with multiple myeloma using adhesive capsaicin 8% patch. Methods We opted for a retrospective observational case series. Between October 2017 and October 2020, we collected clinical data from adult multiple myeloma patients affected by CIPN who were administered the capsaicin 8% patch in our palliative care outpatient clinic. We compiled Numerical Pain Rating Scale (NPRS) scores, patients’ medication needs and performance status before and after patch application. Results Two women and five men with an average age of 62.85 years received bortezomib. Two patients (28.57% of the sample) also received thalidomide. The average NPRS score before patch application was 6.42/10. Five of the seven patients (71.42%) received a mean daily oral morphine dose of 52.85 mg/day, five (71.42%) received gabapentinoids and one (14.28%) received antidepressants. The average NPRS score decreased to 4/10 seven days after patch application, while the mean daily oral morphine dose remained stable. Performance status improved slightly in two patients (28.57%) and remained stable in the rest. One patient (14.28%) required an extra analgesic dose during patch application. Conclusions Capsaicin 8% patch application appears to reduce pain intensity in patients with multiple myeloma suffering from CIPN.