Monday, April 5, 2010

Pain drug from the poisonous cone shell

This stamp was issue by New Caledonia postal authority, on 12 April 2006, to commemorate the centenary of the work by Jules Déjerine and Gustave Roussy, in the field of neuropathalogy, that culminated in the discovery of the Thalamic Pain Syndrome or Central Pain Syndrom, also known as the Déjerine-Roussy Syndrome, allowing latter researchers to work on pain therapeutics. Much work has been conducted on using naturally occurring toxins to combat pain, and among these natural toxins are the conotoxins or toxin secreted by cone shells. This New Caledonian stamp features the shell of Conus geographus, or the geography cone; it is one of the most poisonous cone shell known to man, 70% of recorded untreated stings on human were fatal. The string of letters at the lower-left corner of the stamp is the amino-acid sequence of a peptide extracted from the toxin of the Conus magus, or the magician cone:

CKGKGAKCSRLMYDCCTGSCRSGKC

This peptide is known as the ω-conotoxin MVIIA, also called a ziconitide. It was developed as a drug for intractable pain and was approved by the FDA in December 2004. It is 100 to 1000 times more potent than morphine, available under the trade name of Prialt and it blocks acute pain in patients who no longer obtain relief from opiate drugs; by blocking calcium channels it disables nerves that transmit pain signals. This drug has to be delivered directly to the spinal fluid.

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