Non-opioid analgesics: other: Long-term intrathecal ziconotide effectiveness in chronic malignant and nonmalignant pain

Abstract

The objective of this study was to evaluate the effectiveness of long-term intrathecal (IT) ziconotide (PRIALTTM) therapy in patients with chronic, intractable pain. This phase III, open-label, multicenter extension study included patients with malignant or nonmalignant chronic pain. Patients had demonstrated analgesic response to ziconotide in previous placebo-controlled trials. Patients were maintained on their optimal dose, established in previous trials, for 30 days. Thereafter, dosage adjustments were not to exceed a twofold increase per 12-hour period. Patients indicated level of pain on the Visual Analog Scale of Pain Intensity (VASPI) (0 mm, no pain to 100 mm, worst pain possible). Ziconotide effectiveness was assessed at monthly intervals and at discontinuation from the study via mean percent change from baseline (defined as initial pre-treatment VASPI score from previous trials). A total of 145 patients received ziconotide and had at least 1 efficacy assessment during treatment. Mean patient age was 55 years (range, 24-85 years). Mean ziconotide dosage was 0.6 mcg/h or 14.4 mcg/d (range, 0.05-6.67 mcg/h) at study initiation and 0.5 mcg/h or 12 mcg/d (range, 0.03-6.67 mcg/h) at study termination. By Week 4, mean percentage change in VASPI was statistically significant in 139 evaluable patients (mean change, 37.2%, P<0.0001). This statistically significant improvement in level of pain was maintained through Month 12 in 31 evaluable patients (mean change, 45.8%, P<0.0001) and the last available observation for 144 evaluable patients (mean change, 36.9%, P<0.0001). Mean ziconotide dosage at Month 12 among the 31 evaluable patients was 0.6 mcg/h or 14.4 mcg/d (range, 0-3 mcg/h). Patients treated with IT ziconotide showed significant improvement from baseline at all monthly assessments from Week 4 through Month 12 of treatment. Stable mean dose requirements in conjunction with sustained VASPI reductions suggest the potential for long-term analgesic benefit.