Effective devices and methods using a chemonucleolysis agent are provided for treating an intervertebral disc or treating spinal arachnoiditis. The devices and methods comprise a chemonucleolysis agent to degrade or to shrink at least a portion of the intervertebral disc. In some embodiments, the methods and devices are configured to immediately release an effective amount of the chemonucleolysis agent within 24 hours and provide sustained release of the chemonucleolysis agent over a period of up to one year to treat the intervertebral disc. In some embodiments, the chemonucleolysis agent in the device is administered in or near the intrathecal space and/or thecal sac to treat spinal arachnoiditis.