Researchers have revealed that spider venom may contain a long-sought secret ingredient for an effective, long-term painkiller.
In lab-dish tests, seven compounds obtained from venom blocked a protein crucial for transmitting the sensation of pain to the human brain.
"The hunt for a medicine based on just one of these compounds, which would open up a new class of potent painkillers, is now a step closer," said a statement issued with the study published by the British Journal of Pharmacology.
The poison arachnids use to kill their prey contains molecules that can impair proteins transporting signals between the nerves and the brain.
If it could be targeted and controlled, this "off switch" may be the solution for millions of chronic pain sufferers.
One protein in particular, dubbed Nav1.7, is believed to be the "channel" essential for transmitting pain signals in humans.
"Previous research shows indifference to pain among people who lack Nav1.7 channels due to a naturally-occurring genetic mutation -- so blocking these channels has the potential of turning off pain in people with normal pain pathways," said study leader Glenn King from the University of Queensland, Australia.
The team screened venom from 206 spider species, and found seven compounds that could block human Nav1.7 channels in lab tests.
Of the seven, one was particularly potent "and also had a chemical structure that suggested it would have high levels of chemical, thermal and biological stability, which would be essential for administering a new medicine," said the statement from publishing house Wiley.
"Together, these properties make it particularly exciting as a potential painkiller."
Existing drugs are limited in their efficacy and have dose-limiting side effects.
The study said chronic pain affected some 15 percent of the adult population, with an economic cost to the United States alone of about $600 billion (540 billion euros) per year.
There are about 45,000 species of spider in the world, carrying around a potential nine million-plus peptides of which only about 0.01 percent have been explored by drug researchers.