Intrathecal ziconotide in the treatment of chronic nonmalignant pain: a randomized, double-blind, placebo-controlled clinical trial.

Objective.  The safety and efficacy of intrathecal (IT) ziconotide was studied in a randomized, double-blind, placebo-controlled trial. Materials and Methods.  Patients (169 ziconotide, 86 placebo) with severe chronic nonmalignant pain unresponsive to conventional therapy and a visual analog scale of pain intensity (VASPI score) ≥ 50 mm were treated over a 6-day period in an inpatient hospital setting. Initial starting dose was 0.4 µg/hour and was titrated to analgesia or intolerance (maximum dose 7.0 µg/hour). The starting and maximum doses were reduced to 0.1 µg/hour and 2.4 µg/hour, respectively, due to adverse events (AEs). Results.  The mean percent reduction in VASPI score from baseline was 31.2% and 6.0% for ziconotide- and placebo-treated patients, respectively (p ≤ 0.001). During the initial titration phase, a significantly greater percentage of patients in the ziconotide group compared to the placebo group reported AEs, including abnormal gait, amblyopia, dizziness, nausea, nystagmus, pain, urinary retention, and vomiting. Conclusion.  Ziconotide provided significant analgesia in patients for whom conventional therapy failed. However, there was a considerable incidence of ziconotide-associated AEs due to the rapid titration and high doses administered.