Ziconotide

What is Ziconotide?#

Ziconotide (brand name Prialt) is a synthetic peptide analgesic approved by the FDA in December 2004 for the management of severe chronic pain. It is the synthetic form of omega-conotoxin MVIIA, a 25-amino acid peptide naturally produced in the venom of the marine cone snail Conus magus. Ziconotide is the first and only non-opioid intrathecal analgesic approved by the FDA.

Ziconotide must be administered via continuous intrathecal infusion using an implanted programmable pump or external microinfusion device, as it does not cross the blood-brain barrier when given systemically. It is indicated for patients with severe chronic pain who are intolerant of or refractory to other treatments, including systemic analgesics, adjunctive therapies, or intrathecal morphine.

Mechanism of Action#

Ziconotide selectively and reversibly blocks N-type voltage-gated calcium channels (Cav2.2) located on presynaptic nerve terminals in the dorsal horn of the spinal cord. By blocking calcium influx through these channels, ziconotide inhibits the release of pro-nociceptive neurotransmitters including glutamate, calcitonin gene-related peptide (CGRP), and substance P. This interrupts pain signal transmission from peripheral nociceptors to the central nervous system.

The N-type calcium channel selectivity distinguishes ziconotide from other calcium channel blockers. Unlike L-type blockers used in cardiovascular medicine, ziconotide does not affect cardiac or vascular smooth muscle calcium channels. The peptide contains three disulfide bonds (Cys1-Cys16, Cys8-Cys20, Cys15-Cys25) that constrain its three-dimensional structure and are essential for receptor binding.

Clinical Efficacy#

Three pivotal randomized, double-blind, placebo-controlled Phase 3 trials established ziconotide efficacy in over 600 patients. In the Staats 2004 trial (PMID: 14709577), patients with cancer or AIDS pain showed 53% improvement in pain scores with ziconotide versus 18% with placebo. The Rauck 2006 trial (PMID: 16716870) demonstrated that slow titration improved tolerability while maintaining efficacy (14.7% vs 7.2% VASPI improvement, p=0.036).

Important Considerations#

Ziconotide has a black box warning for severe psychiatric symptoms including psychosis, hallucinations, and suicidal ideation. It is contraindicated in patients with a history of psychosis. CNS adverse effects including dizziness, confusion, and cognitive impairment are common and dose-related. Slow titration from low starting doses significantly improves tolerability. Ziconotide requires specialized intrathecal delivery systems and monitoring by experienced pain management physicians.

Key Research Findings#

Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS: a randomized controlled trial, published in JAMA (Staats PS et al., 2004; PMID: 14709577):

• The study demonstrated mean VASPI improvement with ziconotide of 53.1% vs 18.1% placebo
• The study demonstrated moderate to complete pain relief in of 52.9% vs 17.5% of patients

A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic pain, published in Journal of Pain and Symptom Management (Rauck RL et al., 2006; PMID: 16716870):

• The study demonstrated mean VASPI improvement of 14.7% vs 7.2% placebo

Intrathecal ziconotide in the treatment of chronic nonmalignant pain: a randomized, double-blind, placebo-controlled clinical trial, published in Neuromodulation (Wallace MS et al., 2006; PMID: 22151630):

• The study demonstrated mean VASPI improvement of 31.2% vs 6.0% placebo

Related Reading#

• Ziconotide research studies and evidence
• Ziconotide dosing protocols
• Ziconotide side effects profile
• BPC-157 research guide
• DSIP research guide