Ziconotide for Patients with Painful Myelopathies and Neuropathies

Promising results from a small study suggest that ziconotide, administered either via intrathecal administration or via continuous pump for patients who already have an intrathecal delivery system in place, provides significant pain relief for patients with refractory painful myelopathies and neuropathies, according to research presented at the 65^th Annual Meeting of the American Academy of Neurology.

Ziconotide is a novel, non-opioid, N-type selective calcium channel inhibitor that is thought to work by reversibly blocking the release of pain-associated neurotransmitters from primary nociceptive afferent neurons that end in the dorsal horn of the spinal cord. Due to its side effect profile and reduced efficacy when administered orally or intravenously, ziconotide is administered intrathecally directly into the cerebrospinal fluid. Given the inherent risks of this administration method, it is used to treat severe chronic pain and for patients who are intolerant of or refractory to other treatments. For many patients with refractory neuropathies and myelopathies, however, intrathecal administration of ziconotide in an outpatient setting could represent an additional option for pain relief.

Jacqueline Nicholas, MD, of the Ohio State University Multiple Sclerosis Center in Columbus, Ohio, and colleagues conducted a retrospective chart review study of 11 patients with refractory neuropathic pain due to painful myelopathy, painful neuropathy, or spastic cerebral palsy to evaluate the efficacy of outpatient intrathecal administration of ziconotide. Three patients were already receiving intrathecal baclofen for spasticity via a Synchromed II pump and, therefore, received treatment via pump, rather than lumbar puncture.

During the study, from January 2010 to April 2012, patient scores on the Pain-Numerical Rating Scale (P-NRS) significantly improved from baseline as early as four hours post-injection and continued to improve throughout the duration of the trial. On average, pain returned after 25.5 ±14 hours. Additionally, Patient Global Impression of Change (PGIC) was also statistically significantly improved. Overall, the treatment was generally safe and well tolerated, with one patient experiencing emesis and ataxia, two patients reporting urinary retention, and one patient experiencing urinary incontinence.

“The data also support the use of a catheter aspiration port technique rather than invasive lumbar puncture for patients who already have intrathecal delivery systems in place for other reasons. These results provide preliminary data supporting the efficacy and safety of outpatient administration of a single bolus shot of intrathecal ziconotide in patients with medically refractory painful myelopathies or neuropathies. These results must be interpreted cautiously and replicated in a prospective, placebo-controlled, blinded fashion using a larger sample size. Such a study is being planned and will soon be underway at our institution,” the authors concluded.