The marine cone nail Conus victoriae is venomous to its prey (and humans), but Australian researchers have isolated a non-addictive, pain-relieving chemical from its saliva. This cyclized peptide, known as α-conotoxin cVc1.1, can be ingested orally in pill form.
David J. Craik of the Institute for Molecular Bioscience at the University of Queensland led the research team that created this painkilling conotoxin, or a peptide toxin. From Bethany Halford at Chemical & Engineering News:
The mollusks use a deadly dose of conotoxins-peptide toxins that disrupt myriad biological functions-that they inject into passing prey with hypodermic-needle-like teeth that shoot from their mouths like harpoons [...] Within the conotoxin brew are several peptides that relieve tough-to-treat neuropathic pain just as well as morphine does but without its addictive properties. Although scientists have tried to turn such compounds into pain relievers, they've been hamstrung with problems administering such drugs. The pain reliever Prialt, for example, is a synthetic version of ω-conotoxin MVIIA, but it must be injected directly into the spinal cord with a surgically implanted pump.
Later in the article, Professor Jon-Paul Bingham of the University of Hawaii, Manoa comments that an orally ingestible pill painkiller as powerful as Prialt "would absolutely revolutionize how we manage chronic and terminal pain." Thank you, cone snail. You are a giving, albeit terrifying, creature.