Venom of a sea snail could be used to create a pain relief drug stronger than morphine, scientists say.
Scientists have reported creating five new "experimental substances" based on a tiny protein derived from the venom of a cone snail.
The substances, which could potentially be stronger than morphine, could one day lead to the development of a drug to treat chronic nerve pain, they said.
Lead author Professor David Craik, from the University of Queensland in Australia, said: "This is an important incremental step that could serve as the blueprint for the development of a whole new class of drugs capable of relieving one of the most severe forms of chronic pain that is currently very difficult to treat."
Cone snails are marine animals that use venom to paralyse their prey.
The venom contains hundreds of small proteins known as conotoxins which appear to have an analgesic effect in humans, he said.
Prof Craik and his team, who will present their finding at an American Chemical Society conference, are working to develop a conotoxin-based drug that can be taken orally - unlike the only drug that uses the protein now which must be injected into a patient's spine.
Experiments on rats have shown that a prototype drug has been shown to "significantly reduce pain", he said.
"We don't know about side effects yet, as it hasn't been tested in humans. But we think it would be safe," Prof Craik said.
"It acts by a completely different mechanism than morphine so we think it has a minimal possibility of producing the side-effects of that medication. That is one of the big advantages of this drug."