An Open-Label, Multicenter Study of the Safety and Efficacy of Intrathecal Ziconotide for Severe Chronic Pain When Delivered via an External Pump.

Objectives.  The study aims to assess the safety and efficacy of intrathecal (IT) ziconotide when delivered via an external infusion system. Materials and Methods.  Patients with severe chronic pain were implanted with an external infusion system, and IT ziconotide was titrated over one to four weeks. Safety was evaluated via adverse event (AE) reports, and efficacy measures included the visual analog scale of pain intensity (VASPI), categorical pain relief scale (CPRS), and clinical global impression (CGI). Results.  Sixty-four of the 71 patients (90.1%) experienced an AE during titration; five patients developed meningitis after completing at least two weeks of therapy. A significant (p ≤ 0.005) median percentage improvement in VASPI scores was seen at week 1 and maintained through week 4 (range: 11.0-32.6%); 53.6% of patients reported good to excellent pain control on the CGI and 52.2% of patients reported moderate to complete pain relief on the CPRS. Conclusions.  The study results suggest that a short-term trial of IT ziconotide using an external infusion system may be sufficient to assess patient response. High rates of AEs were noted; however, ziconotide-related AEs were consistent with those reported in previous trials.