Scientists in Australia have developed an oral pain reliever containing a component of sea snail saliva. Information on this subject is published by the Chemical & Engineering News weekly.
Sea snails – cones – do not differ much from their terrestrial cousins in terms of their slowness. Therefore, in order to catch, for example, an agile fish, they developed a whole arsenal of chemical weapons. To paralyze their prey, these mollusks use conotoxins that disrupt various life functions. They inject them under the skin with the help of a needle-thin tooth (the so-called venom arrow), which they eject from the mouth quickly like a harpoon.
Previous studies have shown that some conotoxins can relieve severe and unbearable neuropathic pain (ie, from nerve damage) in a manner similar to morphine, but without its addictive effect.
Therefore, scientists have been trying to use them as painkillers in medicine for some time. However, they did encounter problems – as peptides (ie protein-like compounds only much shorter), conotoxins are unstable and difficult to obtain in an oral form. For example, a pain reliever called Prialt, which is a synthetic version of one of these toxins, has to be injected into the spinal cord, which greatly limits its use.
Australian researchers at the University of Queensland have now managed to chemically modify another painkiller conotoxin so that it can be taken orally. The change consisted in obtaining this compound in a cyclic form. Tests in rats have shown that the new drug is as effective in the treatment of neuropathic pain as the most commonly used gabapanthin, despite the fact that it was administered at a much lower dose.
According to Jon-Paul Binham of the University of Hawaii at Manoa, the potent oral pain reliever Prialt could revolutionize chronic pain management.
The work of scientists from Australia is also valuable for another reason – it creates opportunities for wider use of peptides in the form of oral drugs. As lead author David J. Craik reminds us, few therapeutic peptides today can be used conveniently. This can be changed thanks to the popularisation of a simple method of obtaining cyclic forms of peptides with larger molecules. (PAP)