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Venom used to paralyse their prey: The carnivorous tropical marine cone snail. Photo: Supplied

A new drug extracted from snail venom could provide a breakthrough in treating severe chronic pain without the risk of addiction and dangerous side effects, researchers have found.

The venom - considered 100 times stronger than morphine - could lead to the development of a new class of oral drugs used to relieve nerve pain associated with injury, cancer, AIDS and other diseases.

''It's a very exciting discovery which has the potential to be a blueprint for other protein-based medication,'' David Craik, lead researcher and professor of biomolecular structure at the University of Queensland, said.

The prototype drug, which has been tested on rats, is taken from carnivorous tropical marine cone snails, which use their venom to paralyse their prey. The venom contains hundreds of peptides, or ''mini proteins'', known as conotoxins, which have a pain-killing effect.

''Snails have had 60 million years of evolution to fine-tune their venom, which contains some very powerful molecules,'' said Professor Craik, who will present his findings at an American Chemical Society meeting this week.

''If we can tap into that then it saves us having to do the hard work that evolution has already done for us,'' he said.

A preliminary study using tiny proteins from the venom ''appears to significantly reduce pain'' in lab rats, he said. ''Our digestive system is designed to break down proteins. What we've done is taken a protein and re-enginered it to make it stable enough to work orally.''

Only one conotoxin-derived drug, ziconotide, has been approved for human use but it must be injected into the spine.