Efficacy and Safty of Long Acting Beraprost (TRK-100STP) for Lumbar Spinal Canal Stenosis with Intermittent Claudication : a Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

INTERVENTION: Placebo TRK‐100STP 120ug/day TRK‐100STP 240ug/day CONDITION: Acquired degenerative lumbar spinal canal stenosis PRIMARY OUTCOME: 1.Efficacy outcome measures ; Objective assessments ; Subjective assessments ; QOL assessments ; 2.Safety outcome measures ; Adverse events ; Laboratory values ; Vital signs INCLUSION CRITERIA: (1)Patients with spondylotic or degenerative spondylolosthetic LSCS, who does not have degenerative scoliotic and spondylolytic spondylolisthetic findings. (2)Patients have cauda equine lesion type (cauda equine type or mixed type) symptoms.