Early Real-World Use of Mirogabalin in Japan: A Retrospective Single-Center Cohort Study of Initial Prescribing Patterns

· Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting toxicity affecting over two-thirds of patients receiving neurotoxic chemotherapy. Mirogabalin, a novel gabapentinoid with higher binding affinity to the calcium channel α ₂ δ subunit than pregabalin, was approved in Japan in April 2019 for peripheral neuropathic pain. Real-world data on its early use, particularly for CIPN, remain limited. This study aimed to describe initial prescription patterns and outcomes of mirogabalin at a single Japanese university hospital. · Methods: We conducted a retrospective, single-center, observational cohort study at Toyama University Hospital, including all patients who were newly prescribed mirogabalin between April 15 and November 14, 2019 (N = 143). Data on demographics, prescribing department, and setting (outpatient vs. inpatient), indications, treatment duration, and reasons for discontinuation were extracted from electronic medical records. Effectiveness was defined pragmatically: continuation ≥28 days or explicit documentation of benefit. Descriptive statistics summarized the findings. Ethical approval was obtained (approval no. R2020046). · Results: Median age was 69 years (range, 18–89; 51% male). Mirogabalin was most often initiated in the outpatient setting. The top prescribing department was gastroenterology (including oncology), followed by orthopedics, anesthesiology/pain clinics, and other departments. Over half of the patients had cancer. The primary indications were CIPN, followed by nerve root/spinal neuropathic pain, cancer-related pain, and other neuropathic pain etiologies. No prescriptions were for diabetic peripheral neuropathic pain. By the end of follow-up, 68 patients had discontinued mirogabalin, mainly owing to adverse events (predominantly somnolence and dizziness), followed by sufficient symptom improvement, lack of efficacy, and other reasons. Despite the high discontinuation rate, 101 patients met the composite effectiveness criteria. · Conclusions: In this early real-world cohort, mirogabalin was frequently prescribed for CIPN, radiculopathy, and cancer-related neuropathic pain, rather than for diabetic neuropathy in Japan. Approximately 70% of patients met pragmatic effectiveness criteria, and over one-quarter discontinued use owing to tolerability issues (primarily central nervous system side effects). These findings suggest that mirogabalin addresses an unmet need in cancer-related neuropathic pain, with effectiveness comparable to that reported for pregabalin in similar populations, warranting further studies to confirm efficacy, safety, and comparative performance in prospective trials.