Claimed effect · Ziconotide

Does Ziconotide help with severe cancer or AIDS-related pain?

B
Grade B — probable, not settled1 phase 3 RCT (n=111) · effect size: moderate
Short answerProbable, not settled. Human data exist (1 phase 3 RCT (n=111)) and mostly agree, showing a moderate effect — but too few, too small, or not yet peer-reviewed for a firm answer. A randomised placebo-controlled trial in 111 patients with severe pain despite intrathecal opioids found a mean 53.1% improvement in pain scores against 18.1% on placebo, sustained through the maintenance phase. The result is real and the record is messy: JAMA later published a notice of duplicate publication about this article and an accompanying editorial.

What the studies show

A randomised placebo-controlled trial in 111 patients with severe pain despite intrathecal opioids found a mean 53.1% improvement in pain scores against 18.1% on placebo, sustained through the maintenance phase. The result is real and the record is messy: JAMA later published a notice of duplicate publication about this article and an accompanying editorial.

“Mean VASPI scores improved 53.1% (95% confidence interval [CI], 44.0%-62.2%) in the ziconotide group and 18.1% (95% CI, 4.8%-31.4%) in the placebo group (P<.001), with no loss of efficacy of ziconotide in the maintenance phase.”

Verbatim, from the abstractStaats PS, Yearwood T, Charapata SG, et al. Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS: a randomized controlled trial. JAMA, 2004;291:63–70

Human trials exist and mostly agree, but there are too few of them, they are too small, or one big one is still reading out. Expect the grade to move.

  1. 1
    Staats PS, Yearwood T, Charapata SG, et al. Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS: a randomized controlled trial.JAMA, 2004;291:63–70111 randomised. See the duplicate-publication notice below before citing this trial's size or novelty.
  2. 2
    Notice of duplicate publication.JAMA, 2004The journal's notice concerning the ziconotide trial above.
  3. 3
    Duplicate publication, multiple problems (editorial).JAMA, 2004Editorial accompanying the notice.

In context

Ziconotide is a synthetic copy of a 25-amino-acid peptide from the venom of the cone snail Conus magus, approved as Prialt in 2004 for severe chronic pain in people who need intrathecal therapy. It blocks N-type calcium channels in the spinal cord — a mechanism unrelated to opioids, with no tolerance and no dependence. In its cancer and AIDS pain trial, pain scores improved 53.1% against 18.1% on placebo. It carries a boxed warning for severe psychiatric and neurological effects.

Ziconotide is approved (rx). Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is Ziconotide proven to help with severe cancer or AIDS-related pain?
Not yet settled. 1 phase 3 RCT (n=111) — LYO grades it B, meaning probable but liable to change as trials read out.
What studies are behind the grade?
A randomised placebo-controlled trial in 111 patients with severe pain despite intrathecal opioids found a mean 53.1% improvement in pain scores against 18.1% on placebo, sustained through the maintenance phase. The result is real and the record is messy: JAMA later published a notice of duplicate publication about this article and an accompanying editorial.
Is Ziconotide approved for this?
Ziconotide is an approved medicine (Approved (Rx)); whether this particular outcome is a licensed indication is stated on the compound page's regulation section.

Other outcomes for Ziconotide

Written and maintained by LYO Research — how pages are written and checked. Reviewed 29 October 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →