Considerations and methodology for trialing ziconotide

Before long-term intrathecal analgesic therapy is initiated, patients often undergo a spinal analgesia trial. Ziconotide is a nonopioid intrathecal analgesic used to manage severe chronic pain, and a variety of methods have been used to trial ziconotide.

The purpose of this review is to compare and discuss the different methods of ziconotide trialing.

Various databases (i.e., PubMed, Excerpta Medica, Cumulative Index to Nursing and Allied Health Literature, Biological Abstracts, Cochrane Database of Systematic Reviews, EMBASE, International Pharmaceutical Abstracts, and Google Scholar) and association meeting abstracts were searched with the use of the terms ziconotide, Prialt, trial, and trialing. In addition, a search was conducted for abstracts/posters presented at a variety of association meetings.

Nine sources, including one expert opinion piece, were identified. Three methods of ziconotide trialing were discovered: continuous infusion, limited-duration infusion, and bolus injection. Results indicate that patients often achieve analgesia during trialing, regardless of the trialing method. Adverse events reported during ziconotide trialing studies were similar to those reported during ziconotide clinical trials. Preliminary evidence suggests that both effectiveness and safety may be dose-related. In 3 studies the value of ziconotide trialing in predicting long-term patient response to ziconotide therapy was investigated; however, the results were preliminary. The expert opinion piece from 2008 recommended trialing ziconotide via continuous infusion, using a starting dose of 1.2 mcg/d and dose increases of 1.2 mcg/d every 12 to 24 hours, for up to 3 days; the trial may be extended in some cases.

Given the small samples size and lack of controlled ziconotide trialing studies, it is currently not possible to determine the relative safety and effectiveness of different methods of ziconotide trialing, nor is it possible to determine if trialing is predictive of patient response to long-term ziconotide therapy.

All 3 methods of ziconotide trialing appear to be viable options, and no method can be considered superior on the basis of the evidence presented in this review. Controlled studies comparing ziconotide trialing methods may be warranted.