Epidural injection of dexamethasone palmitate vs. betamethasone for lumbar radiculopathy, study protocol for a multi-center non-inferiority randomized double-blind controlled trial.

Introduction: Lumbar disc herniation is commonly treated with epidural steroid injections to relieve radicular pain. Dexamethasone palmitate, a newer lipophilic formulation, is theoretically safer and provides longer-lasting effects compared to traditional corticosteroids like betamethasone. However, direct clinical evidence comparing their efficacy and safety is still limited. Methods: This multicenter, randomized, double-blind, non-inferiority trial will enroll 228 patients with confirmed lumbar disc herniation and radicular pain. Participants will be randomly assigned (1:1) to receive an image-guided epidural injection of either DEP or compound betamethasone via interlaminar or transforaminal approach. Follow-up assessments will occur at 1 day, 1 week, 2 weeks, 4 weeks, 8 weeks, and 12 weeks post-injection. The primary outcome is leg pain intensity at 4 weeks, measured by the numeric rating scale (NRS). Secondary outcomes include NRS at other time points, functional disability (ODI and RMDQ), mental health (GAD-7 and PHQ-9), morning serum cortisol, patient satisfaction, and adverse events. A second injection may be administered at 4 weeks based on clinical response. Expected outcomes: This study will provide the first high-quality evidence on the efficacy and safety of DEP compared with standard particulate corticosteroids for lumbar radiculopathy. Findings are expected to inform clinical decision-making and optimize steroid selection for epidural therapy. Clinical Trial registration: [https://www.chictr.org.cn], identifier [ChiCTR2400093970].