Corticosteroid Lumbar Epidural Analgesia for Radicular Pain 2

This is a research study of SP-102, an experimental medication designed to relieve pain in patients with moderate to severe sciatica (pain in the lower back, hips, buttocks and legs). SP-102, placebo (a medication that looks like SP-102 but does not contain any active ingredient), or an active comparator (dexamethasone sodium phosphate) is given once by the participant's healthcare professional. If a participant meets qualifications, each participant will have the option of receiving one supplemental open-label injection of SP-102, greater than four weeks and up to twenty weeks after their first injection. The purpose of the study is to measure how well a single injection of the experimental medication, SP-102, relieves pain versus placebo. The study will also measure how well SP-102 relieves pain versus an active comparator medication (dexamethasone sodium phosphate). The study will also investigate the side effects of SP-102.