|Systematic (IUPAC) name|
|Routes||Intrathecal – directly into cerebrospinal fluid by a catheter|
|Half-life||2.9 to 6.5 hours|
|Molecular mass||2639 daltons|
|(what is this?)|
Ziconotide (SNX-111; Prialt) is an atypical analgesic agent for the amelioration of severe and chronic pain. Derived from Conus magus (Cone Snail), it is the synthetic form of an ω-conotoxin peptide.
Ziconotide is derived from the toxin of the cone snail species Conus magus. Scientists have been intrigued by the effects of the thousands of chemicals in marine snail toxins since the initial investigations in the late 1960s by Baldomero Olivera. Olivera, now a professor of biology in the University of Utah, was inspired by accounts of the deadly effects of these toxins from his childhood in the Philippines. Ziconotide was discovered in the early 1980s by University of Utah research scientist Michael McIntosh, when he was barely out of high school and working with Baldomero Olivera.
Ziconotide was developed into an artificially manufactured drug by Elan Corporation. It was approved for sale under the name Prialt by the U.S. Food and Drug Administration on December 28, 2004, and by the European Commission on February 22, 2005. Azur Pharma acquired worldwide rights (except Europe) to Prialt in 2010.
Mechanism of action
Ziconotide is a hydrophilic molecule that is freely soluble in water and is practically insoluble in methyl t-butyl ether. Ziconotide acts as a selective N-type voltage-gated calcium channel blocker. This action inhibits the release of pro-nociceptive neurochemicals like glutamate, calcitonin gene-related peptide (CGRP), and substance P in the brain and spinal cord, resulting in pain relief.
Due to the profound side effects or lack of efficacy when delivered through more common routes, such as orally or intravenously, ziconotide must be administered intrathecally (i.e. directly into the spinal fluid). As this is the most expensive and invasive method of drug delivery and involves additional risks of its own, ziconotide therapy is generally considered appropriate (as evidenced by the range of use approved by the FDA in US) only for “management of severe chronic pain in patients for whom intrathecal (IT) therapy is warranted and who are intolerant of or refractory to other treatment, such as systemic analgesics, adjunctive therapies or IT morphine”. In practice, the efficacy of ziconotide in relieving neurogenic pain remains to be established, according to Prescrire International, October 2008. Furthermore "It is better to re-examine and, if possible, correct the reasons for opiate treatment failure rather than prescribe ziconotide."
However, this must be weighed against the high level of pain management, both in terms of degree and length, and the apparent lack of tolerance and other signs of dependence even after extended treatment along with the need for alternatives to other therapies that have not worked for the patient. Ziconotide is also contraindicated for patients with certain preexisting mental disorders (e.g. psychosis) due to evidence that they are more susceptible to certain severe side effects.
The most common side effects are dizziness, nausea, confusion, nystagmus and headache. Others may include weakness, hypertonia, ataxia, abnormal vision, anorexia, somnolence, unsteadiness on feet, vertigo, urinary retention, pruritis, increased sweating, diarrhea, nausea, vomiting, asthenia, fever, rigors, sinusitis, muscle spasms, myalgia, insomnia, anxiety, amnesia, nystagmus, tremor, memory impairment and induced psychiatric disorders. Other side effects which are less frequent but still clinically significant include auditory and visual hallucinations, thoughts of suicide, acute renal failure, atrial fibrilation, cardiovascular accident, sepsis, new or worsening depression, paranoia, disorientation, meningitis and seizures. Therefore, it is contraindicated in people with a history of psychosis, schizophrenia, clinical depression, and bipolar disorder. Recent incidents suggesting a link between intrathecal ziconotide treatment and increased risk of suicide have led to calls for strict and ongoing psychiatric monitoring of patients to avoid suicide occurring in vulnerable individuals. There is no known antidote.
The drug was patented by Neurex Corp., a U.S. company purchased in 1998 by Élan Corporation, plc of Ireland. U.S. patents assigned to Elan include 5,859,186, 5,795,864, 5,770,690, 5,587,454, and 5,559,095.
- Skov MJ, Beck JC, de Kater AW, Shopp GM (2007). "Nonclinical safety of ziconotide: an intrathecal analgesic of a new pharmaceutical class". Int. J. Toxicol. 26 (5): 411–21. doi:10.1080/10915810701582970. PMID 17963128.
- McIntosh M, Cruz LJ, Hunkapiller MW, Gray WR, Olivera BM (1982). "Isolation and structure of a peptide toxin from the marine snail Conus magus". Arch. Biochem. Biophys. 218 (1): 329–34. doi:10.1016/0003-9861(82)90351-4. PMID 7149738.
- "NIGMS – Findings, September 2002: Secrets of the Killer Snails". Retrieved 2007-12-21.
- Miljanich GP (2004). "Ziconotide: neuronal calcium channel blocker for treating severe chronic pain.". Curr Med Chem 11 (23): 3029–40. doi:10.2174/0929867043363884. PMID 15578997.
- McGivern JG (2007). "Ziconotide: a review of its pharmacology and use in the treatment of pain.". Neuropsychiatr Dis Treat 3 (1): 69–85. doi:10.2147/nedt.2007.3.1.69. PMC 2654521. PMID 19300539.
- "Medscape". Retrieved 2007-12-21.
- "U.S. Pharmacist". Retrieved 2007-12-21.
- Prommer E (2006). "Ziconotide: a new option for refractory pain". Drugs Today 42 (6): 369–78. doi:10.1358/dot.2006.42.6.973534. PMID 16845440.
- Klotz U (2006). "Ziconotide—a novel neuron-specific calcium channel blocker for the intrathecal treatment of severe chronic pain—a short review". Int J Clin Pharmacol Ther 44 (10): 478–83. PMID 17063978.
- Maier C, Gockel HH, Gruhn K, Krumova EK, Edel MA (October 2010). "Increased risk of suicide under intrathecal ziconotide treatment? – A warning". Pain 152 (1): 235–237. doi:10.1016/j.pain.2010.10.007. PMID 21041028.
- Manufacturer website
- FDA approves new drug for severe pain, a December 2004 Associated Press article
- Press release announcing FDA approval from Elan
- Ziconotide Effectiveness and Safety Trial in Patients with Chronic Severe Pain