A randomized, placebo-controlled trial of long-acting dexamethasone viscous gel delivered by transforaminal injection for lumbosacral radicular pain

Abstract

Abstract Epidural steroid injections are used to treat lumbosacral radicular pain. However, there are no Food and Drug Administration–approved corticosteroids for lumbosacral radicular pain and all currently available injectable corticosteroids carry safety warnings about their use in epidural steroid injection procedures. SP-102 (dexamethasone injectable viscous gel) was developed to provide a safer option with extended local effect. In a randomized, double-blind, placebo-controlled, multicenter trial, 401 patients with moderate-to-severe leg pain from unilateral intervertebral lumbar disc herniation were randomized (1:1) to receive transforaminal SP-102 or sham intramuscular (IM) placebo injection and followed for 24 weeks. If clinically warranted, a repeat open-label SP-102 injection was allowed between 4 and 20 weeks for both groups. Primary and key secondary end points were change in average daily pain on the Numeric Pain Rating Scale in the affected leg and disability measured by Oswestry Disability Index over 4 weeks. Other secondary end points included time to repeat injection, pain, and quality of life assessments. Over 4 weeks, SP-102 demonstrated statistically significant pain relief compared with placebo (least-squares mean group difference −0.52 [SE 0.163] [P = 0.002]) in the intent-to-treat population. Oswestry Disability Index mean improvement was −3.38 (1.388) (least-squares mean group difference [SE]) for SP-102 vs placebo (P = 0.015). Median time to repeat injection was 84 days for SP-102 vs 58 days for placebo (P = 0.001). Most other secondary end points were statistically significant for SP-102 compared with placebo. There were no serious adverse events related to study medication or procedure, no adverse events leading to death, and no AEs of special interest (paraplegia, hematoma, or infection). Trial Registration ClinicalTrials.gov Identifier: NCT03372161.