Cognitive & neuro
Ziconotide
A cone-snail peptide that blocks pain-conducting calcium channels, delivered only into the spinal fluid by pump.
What it is
Ziconotide is a synthetic version of omega-conotoxin MVIIA, a 25-amino-acid peptide from the venom of the marine cone snail Conus magus. It blocks N-type voltage-gated calcium channels on pain-conducting nerves. It is licensed (Prialt) for severe chronic pain, but only as an intrathecal infusion through an implanted pump, because it does not cross into the nervous system when given any other way.
How it works
- 1
Blocks N-type (Cav2.2) voltage-gated calcium channels on primary pain-sensing neurons.
- 2
Prevents calcium influx and the release of substance P and glutamate in the dorsal horn.
- 3
Reduces pain signalling without acting on opioid receptors.
- 4
Must be delivered into cerebrospinal fluid because it cannot cross the blood-brain barrier.
- 5
Has a narrow therapeutic window, with psychiatric and neurological effects close to the useful dose.
What it's studied for
Reported and studied effects
- Clinically meaningful pain reduction in a subset of patients in randomised trials
- No opioid tolerance or respiratory depression
- Neuropsychiatric effects such as confusion, hallucinations and mood change
- Requires slow titration over weeks
Research protocol notes
Research context onlyResearch context only - an implanted intrathecal pump therapy managed by a pain specialist. Titration starts at 2.4 micrograms per day and increases slowly, with a maximum of 19.2 micrograms per day in most patients and no bolus dosing; trials measured pain intensity and adverse events over 3 to 6 weeks of titration.
These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.
Possible side effects and contraindications
Safety profile
Possible side effects
- Dizziness and confusion
- Nausea and vomiting
- Nystagmus and abnormal gait
- Memory impairment
- Hallucinations and mood change
- Meningitis with pump complications
- Suicidal ideation reported
Contraindications and cautions
- Pre-existing psychosis or severe psychiatric disorder
- Known allergy to ziconotide
- Conditions preventing intrathecal pump use
- Not for intravenous, epidural or intramuscular use
A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.
Evidence assessment
Three randomised placebo-controlled intrathecal trials show analgesia in a subset of patients, but the narrow therapeutic index and small samples limit how strong that evidence can be.
References
- 01Staats et al., Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS, JAMA 2004
- 02European Medicines Agency - Prialt product information
References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.
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