Mechanism of Action
Pharmacological Diversity
Conotoxins are classified by their molecular targets: omega-conotoxins block N-type (Cav2.2) calcium channels; mu-conotoxins block voltage-gated sodium channels; alpha-conotoxins block nicotinic acetylcholine receptors; delta-conotoxins delay Na+ channel inactivation; kappa-conotoxins block K+ channels. This diversity makes conotoxins the most pharmacologically diverse natural peptide library known.
Ziconotide Mechanism
Ziconotide selectively and reversibly blocks N-type (Cav2.2) voltage-gated calcium channels in the dorsal horn of the spinal cord. N-type channels mediate calcium entry triggering synaptic vesicle release of pain neurotransmitters (substance P, glutamate) at presynaptic terminals of nociceptive C-fibers. Blockade interrupts pain signal transmission at the spinal level.
Research Summary
Intractable Chronic Pain (Ziconotide)
FDA ApprovedZiconotide (Prialt) is FDA-approved for intractable chronic pain (cancer, HIV, failed back surgery) via continuous intrathecal infusion pump. Unlike opioids, it does not cause tolerance or physical dependence with long-term use, making it valuable for opioid-refractory pain.
Drug Discovery Platform
Active ResearchConotoxins represent one of the most active areas of peptide drug discovery. Alpha-conotoxins targeting specific nAChR subtypes are leads for nicotine addiction, pain, and schizophrenia. The diversity of Conus venom libraries is still largely unexplored, with thousands of sequences potentially representing novel pharmacology.
Cardiovascular Research
PreclinicalOmega-conotoxin GVIA and SVIB block N-type and P/Q-type calcium channels in cardiac preparations, providing tools for dissecting calcium channel subtypes in cardiovascular physiology.
Calculate your Conotoxin dose Vial strength, BAC water, exact syringe draw in IU. Free, no signup. Open Calc →
Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Intractable pain (ziconotide intrathecal) | Start 0.1 mcg/hr, titrate up to 0.8 mcg/hr max | Continuous intrathecal infusion | Intrathecal pump |
| N-type Ca channel blockade (patch clamp) | 0.1-100 nM (omega-conotoxin GVIA) | Continuous bath application | In vitro |
| nAChR subtype pharmacology (alpha-conotoxin) | 1-1000 nM | Single concentration-response | In vitro (Xenopus oocyte or cell-based) |
Ziconotide requires intrathecal pump implantation and specialist pain clinic management. Other conotoxins are research tools only.
Interactions
Safety Profile
Ziconotide causes significant CNS side effects including dizziness, nausea, confusion, and psychiatric symptoms (depression, hallucinations) requiring slow titration and careful monitoring. Contraindicated in patients with history of psychosis. Intrathecal administration limits systemic exposure. Other conotoxins are research tools with acute toxicity sufficient to paralyze or kill prey.
References
- [1]Olivera BM, et al. Peptide neurotoxins from fish-hunting cone snails. Science. 1985;230(4732):1338-1343.
- [2]Staats PS, et al. Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS: a randomized controlled trial. JAMA. 2004;291(1):63-70.
- [3]Lewis RJ, Garcia ML. Therapeutic potential of venom peptides. Nat Rev Drug Discov. 2003;2(10):790-802.