Ziconotide
Ziconotide (Prialt, SNX-111) is a synthetic 25-amino acid omega-conotoxin MVIIA derived from the venom of the marine cone snail Conus magus. It is a selective N-type voltage-gated calcium channel (Cav2.2) blocker approved for intrathecal administration in severe chronic pain refractory to other therapies.
Overview
Ziconotide emerged from decades of research into cone snail venoms, which contain complex mixtures of bioactive peptides (conotoxins) that target ion channels and receptors with remarkable selectivity. Baldomero Olivera and colleagues at the University of Utah first characterized omega-conotoxin MVIIA in the 1980s, identifying its potent and selective blockade of N-type voltage-gated calcium channels (Cav2.2) at presynaptic terminals in the spinal cord dorsal horn (Olivera et al., 1987).
The peptide's therapeutic potential arises from a fundamental principle of pain neurobiology: nociceptive signal transmission at the first synapse in the spinal cord requires calcium influx through Cav2.2 channels to trigger neurotransmitter release. By blocking these channels, ziconotide interrupts pain signaling without binding opioid receptors, making it a non-opioid analgesic with no risk of respiratory depression, tolerance, or addiction in the classical opioid sense.
However, ziconotide's clinical utility is constrained by its requirement for intrathecal delivery (it does not cross the blood-brain barrier), a narrow therapeutic window, and significant neuropsychiatric side effects that necessitate careful dose titration.
Mechanism of Action
Ziconotide's analgesic mechanism is well characterized:
- Cav2.2 channel blockade: Ziconotide binds with high affinity and selectivity to N-type voltage-gated calcium channels (Cav2.2) on presynaptic terminals of primary afferent nociceptive neurons in the spinal cord dorsal horn (Bowersox et al., 1996). This blocks calcium influx required for vesicular release of pronociceptive neurotransmitters (substance P, glutamate, CGRP).
- Non-opioid mechanism: Unlike morphine and other opioid analgesics, ziconotide does not bind mu, delta, or kappa opioid receptors. This eliminates classical opioid side effects including respiratory depression, constipation, and pharmacological tolerance (Staats et al., 2004).
- Spinal selectivity: Intrathecal delivery targets the peptide directly to dorsal horn Cav2.2 channels. Systemic administration is not viable due to inability to cross the blood-brain barrier and unacceptable peripheral side effects at effective CNS doses.
- Irreversible-like binding kinetics: Ziconotide dissociates extremely slowly from Cav2.2 channels, producing prolonged blockade that necessitates continuous infusion for steady-state analgesia and careful dose titration to avoid accumulation.
Reconstitution Calculator
Research
Severe Chronic Pain
The pivotal clinical trials leading to FDA approval demonstrated ziconotide's efficacy in patients with severe chronic pain refractory to conventional therapies. Staats et al. (2004) conducted a randomized, double-blind, placebo-controlled trial in 111 patients with cancer or AIDS-related pain, showing significant pain reduction (53.1% vs 18.1% improvement) with intrathecal ziconotide (Staats et al., 2004). Rauck et al. (2006) confirmed efficacy in non-malignant chronic pain, though with a narrower effect size and higher rates of adverse events at aggressive titration schedules (Rauck et al., 2006).
Cancer Pain
Ziconotide has shown particular utility in cancer pain management where opioid tolerance or intolerable opioid side effects limit therapy. In the Staats et al. pivotal trial, patients with refractory cancer pain achieved clinically meaningful analgesia. Long-term open-label extensions have demonstrated sustained efficacy over months to years in some patients without the tolerance that characterizes chronic opioid therapy (Wallace et al., 2006).
Neuropathic Pain
Neuropathic pain — arising from nerve damage rather than tissue injury — is mediated substantially through Cav2.2 channels. Preclinical models of neuropathic pain consistently show antiallodynic and antihyperalgesic effects of ziconotide. Clinical data support efficacy in failed-back surgery syndrome, complex regional pain syndrome, and peripheral neuropathy, though psychiatric adverse events limit tolerability in some patients (Ver Donck et al., 2008).
Comparison with Intrathecal Opioids
Ziconotide offers several theoretical advantages over intrathecal morphine: no respiratory depression risk, no pharmacological tolerance development, no opioid-induced hyperalgesia, and no hormonal disruption. However, its narrow therapeutic window and neuropsychiatric side effects make it a second-line agent in most guidelines, reserved for patients who have failed or are intolerant of intrathecal opioids (Pope & Deer, 2013).
N-type calcium channel analgesia
Ziconotide (SNX-111) is a synthetic 25-amino-acid version of omega-conotoxin MVIIA from the marine cone snail Conus magus. It selectively and reversibly blocks N-type (Cav2.2) voltage-gated calcium channels on primary nociceptive afferents in the dorsal horn, reducing release of pain neurotransmitters. Because it does not act on opioid receptors, it produces no tolerance, dependence, or respiratory depression, making it a mechanistically distinct non-opioid analgesic.
- Selective N-type (Cav2.2) calcium channel blockade in the spinal dorsal horn
- No analgesic tolerance or physical dependence with chronic use
- Requires intrathecal delivery due to poor CNS penetration and narrow therapeutic index
Intrathecal dosing optimization
Early trials using rapid titration produced high rates of neuropsychiatric adverse events (dizziness, confusion, nystagmus). Subsequent research established slow titration (low starting doses, small weekly increments) as the standard of care, greatly improving the benefit-risk profile and enabling long-term intrathecal therapy in refractory patients.
- Slow titration reduced adverse events while retaining efficacy
- Low starting doses (~0.5-1.2 mcg/day) with weekly increments now recommended
- Open-label extensions support durable analgesia over 12+ months
Safety Profile
Ziconotide has a narrow therapeutic window that demands slow dose titration and careful patient monitoring. Adverse events are common and dose-dependent:
- Neuropsychiatric: Dizziness, confusion, memory impairment, somnolence, hallucinations, psychosis, suicidal ideation (FDA black box warning for severe psychiatric symptoms)
- Neurological: Nystagmus, abnormal gait, ataxia, headache, speech disorder
- Gastrointestinal: Nausea, vomiting, diarrhea
- Other: Urinary retention, elevated creatine kinase, meningitis (related to intrathecal catheter/pump system)
The FDA label carries warnings regarding new-onset or worsening depression and suicidality. Patients require cognitive assessment before and during therapy. Ziconotide must be delivered via implanted intrathecal infusion pump with slow titration (no more than 2.4 mcg/day increase per week, starting at 0.5 mcg/day or lower). Abrupt withdrawal does not produce a withdrawal syndrome, which is an advantage over intrathecal opioids.
Pharmacokinetic Profile
Ziconotide — Pharmacokinetic Curve
Intrathecal infusion onlyQuick Start
- Route
- Intrathecal infusion only
Molecular Structure
- Formula
- C₁₀₂H₁₇₂N₃₆O₃₂S₇
- Weight
- 2639 Da
- CAS
- 107452-89-1
- PubChem CID
- 16135415
- Exact Mass
- 2638.1017 Da
- LogP
- -14
- TPSA
- 1310 Ų
- H-Bond Donors
- 42
- H-Bond Acceptors
- 46
- Rotatable Bonds
- 40
- Complexity
- 5480
Identifiers (SMILES, InChI)
InChI=1S/C102H172N36O32S7/c1-50(2)34-63-91(161)127-62(26-33-171-5)90(160)129-64(35-53-22-24-54(143)25-23-53)92(162)130-65(36-78(148)149)93(163)135-72-48-175-173-45-69(80(108)150)133-86(156)58(18-8-12-29-105)121-76(146)39-117-85(155)66(41-139)131-88(158)61(21-15-32-114-102(111)112)126-96(166)70-46-176-177-47-71(97(167)132-68(43-141)95(165)125-60(87(157)128-63)20-14-31-113-101(109)110)134-89(159)59(19-9-13-30-106)123-81(151)51(3)119-74(144)37-115-83(153)56(16-6-10-27-103)120-75(145)38-116-84(154)57(17-7-11-28-104)124-82(152)55(107)44-172-174-49-73(137-98(72)168)99(169)138-79(52(4)142)100(170)118-40-77(147)122-67(42-140)94(164)136-70/h22-25,50-52,55-73,79,139-143H,6-21,26-49,103-107H2,1-5H3,(H2,108,150)(H,115,153)(H,116,154)(H,117,155)(H,118,170)(H,119,144)(H,120,145)(H,121,146)(H,122,147)(H,123,151)(H,124,152)(H,125,165)(H,126,166)(H,127,161)(H,128,157)(H,129,160)(H,130,162)(H,131,158)(H,132,167)(H,133,156)(H,134,159)(H,135,163)(H,136,164)(H,137,168)(H,138,169)(H,148,149)(H4,109,110,113)(H4,111,112,114)/t51-,52+,55-,56-,57-,58-,59-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,70-,71-,72-,73-,79-/m0/s1
BPKIMPVREBSLAJ-QTBYCLKRSA-NResearch Indications
Approved Indications
FDA- and EMA-approved (Prialt) for intrathecal management of severe chronic pain in adults intolerant of or refractory to other treatments including systemic analgesics and intrathecal morphine.
Pain Subtypes Studied
Pivotal Phase III trial showed clinically significant analgesia in refractory malignant pain.
Studied in refractory non-cancer pain; effective but limited by CNS side effects and narrow therapeutic window requiring slow titration.
Research Protocols
intrathecal Injection
However, ziconotide's clinical utility is constrained by its requirement for intrathecal delivery (it does not cross the blood-brain barrier), a narrow therapeutic window, and significant neuropsychiatric side effects that necessitate careful dose titration. - Spinal selectivity: Intrathecal deliver
| Goal | Dose | Frequency | Duration |
|---|---|---|---|
| Other | 2.4 mcg, 0.5 mcg | Per protocol | —(Route: Intrathecal) |
Interactions
Peptide Interactions
Ziconotide offers several theoretical advantages over intrathecal morphine: no respiratory depression risk, no pharmacological tolerance development, no opioid-induced hyperalgesia, and no hormonal disruption. However, its narrow therapeutic window and neuropsychiatric side effects make it a seco...
What to Expect
What to Expect
Effects begin within hours of administration based on half-life of ~4.6 hours (CSF)
Due to short half-life (~4.6 hours (CSF)), effects are expected per-dose; consistent daily administration maintains therapeutic levels
Regular administration schedule required; effects are dose-dependent and do not persist between doses
Quality Indicators
What to look for
- Phase 3 clinical trial data available
- Human clinical trials conducted
- Multiple peer-reviewed studies available
Red flags
- Significant side effect risk noted
Frequently Asked Questions
References (13)
- [7]Pope JE, Deer TR Ziconotide: a clinical update and pharmacologic review Expert Opin Pharmacother (2013)
- [2]Bowersox SS et al Selective N-type neuronal voltage-sensitive calcium channel blocker, SNX-111, produces spinal antinociception in rat models of acute, persistent and neuropathic pain J Pharmacol Exp Ther (1996)
- [1]Olivera BM et al Neuronal calcium channel antagonists. Discrimination between calcium channel subtypes using omega-conotoxin from Conus magus venom Biochemistry (1987)
- [4]Rauck RL et al A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic pain J Pain Symptom Manage (2006)
- [6]
- [8]Deer TR et al The Polyanalgesic Consensus Conference (PACC): Recommendations on Intrathecal Drug Infusion Systems Best Practices and Guidelines Neuromodulation (2017)
- [9]
- [3]
- [5]Wallace MS et al Intrathecal ziconotide in the treatment of chronic nonmalignant pain: a randomized, double-blind, placebo-controlled clinical trial Neuromodulation (2006)
- [10]US Food and Drug Administration PRIALT (ziconotide) intrathecal infusion — Prescribing Information FDA Drug Label (2023)
→ Approved intrathecal dosing: initiate at no more than 2.4 mcg/day (0.1 mcg/hr), titrate in increments of up to 2.4 mcg/day no more than 2-3 times per week, maximum 19.2 mcg/day (0.8 mcg/hr).
- [11]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)
→ In 111 patients with refractory cancer or AIDS pain, intrathecal ziconotide produced significantly greater pain relief than placebo (mean VASPI improvement 53.1% vs 18.1%, p<0.001).
- [12]Rauck RL, Wallace MS, Leong MS, et al. A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic pain Journal of Pain and Symptom Management (2006)
→ Using a slow 3-week titration schedule, ziconotide gave greater VASPI improvement than placebo (14.7% vs 7.2%, p=0.036) with markedly better tolerability than earlier fast-titration studies.
- [13]Miljanich GP Ziconotide: neuronal calcium channel blocker for treating severe chronic pain Current Medicinal Chemistry (2004)
→ Reviews ziconotide as a synthetic omega-conotoxin MVIIA that selectively blocks N-type voltage-gated calcium channels, a non-opioid mechanism with no tolerance or dependence.
ZEAXANTHIN
Zeaxanthin is a fat-soluble carotenoid antioxidant that, along with lutein, selectively accumulates in the macula of the eye where it forms macular pigment. It
ZINC
Zinc is an essential trace mineral required for numerous biological functions including immune system support, protein synthesis, wound healing, DNA synthesis,