Ziconotide

Ziconotide, an intrathecal analgesic for the management of chronic intractable pain, binds with high affinity to N-type calcium channels in neuronal tissue and obstructs neurotransmission. In three pivotal, well designed trials of 5-6 or 21 days' duration, titrated ziconotide was significantly more effective than placebo in treating chronic malignant or nonmalignant pain as assessed by mean percentage improvements from baseline in Visual Analogue Scale Pain Intensity scores. Improvements in secondary endpoints (e.g. proportion of patients who responded or achieved pain relief and the change in opioid use) generally support the efficacy of ziconotide over placebo. Ziconotide maintains its analgesic efficacy in preliminary results from long-term, open-label trials (data available for up to 12 months). Most ziconotide-related adverse events are neurological, mild to moderate in severity, resolve over time and reverse without sequelae on drug discontinuation. Low initial doses of ziconotide and gradual titration to onset of analgesia reduces the incidence and severity of adverse events. No evidence of respiratory depression has been reported with intrathecal ziconotide.