Why are there no drugs indicated for sciatica, the most common chronic neuropathic syndrome of all?

This review examines the stark contrast between the successes and failures of the clinical development of analgesics for different types of chronic low back pain (CLBP) syndrome over the past three decades. Multiple drugs with differing mechanisms of action have been developed for nonspecific axial-predominant low back syndromes and yet not a single therapy is indicated for any neuropathic low back pain syndrome (e.g., sciatica). Clinician findings have informed the entry criteria for neuropathic low back pain clinical trials, whereas entry criteria of axial CLBP trials have prioritized only patient reports of pain. This key difference could account for the lack of success in developing therapies for neuropathic low back pain in an era marked by successful development of analgesics for other types of CLBP as well as many chronic pain syndromes associated with nerve injury, such as post-herpetic neuralgia (PHN).