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.