Toxic Medicine: How Venom Can Heal

PHOTO: Saw-scaled viper (Echis carinatus) in Arabia and South Asia is the source of tirofiban (Aggrastat®) one of the cornerstone drug for the treatment of the most lethal types of heart attacks.
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Of the deadly animals in the wild, no pit viper or scorpion quite matches the hidden danger of the 3-inch long Conus magus, or "magician's cone," snail.

On the ocean floor the snail tends to look like a seafaring paperweight, at least until dinner swims by.

Then the formerly unassuming snail uses its snakelike tongue, topped with a tiny harpoon, to inject its prey with immobilizing venom, turning a passing fish into a one-bite meal.

The venom is made up of approximately 200 different kinds of toxins and can kill a grown man as easily as it kills a guppy. Any human unlucky enough to be injected by the venom will be effectively paralyzed by the toxin-filled substance, which can lead to organ failure when the diaphragm muscles are no longer able to contract and pull oxygen into the lungs.

Jon-Paul Bingham, an assistant professor in the department of molecular biosciences and biological engineering at the University of Hawaii, has made a career of studying various species of the cone snail and characterizes them as "pretty horrific, pretty nasty."

But the venom, Bingham said, causes one surprising reaction in its victims: They feel no pain.

This venom's ability to cut off pain receptors has led to a second life as a powerful pain reliever called Prialt. The drug is 1,000 times more potent than morphine and is nonaddictive.

Prialt is just one example of the many ways venom components can be used therapeutically. Currently, six venom-derived medications have been approved by the U.S. Food and Drug Administration, but new technologies and research have shown how proteins and toxins within venom can provide key blueprints for treating a wider variety of ailments, including autoimmune disease, stroke and multiple sclerosis.

Venom-based cures have been around since at least the seventh century B.C., when snake venom was used to treat arthritis and gastrointestinal problems. Modern venom-derived medications started in the 1970s, when pit viper venom was used to create blood pressure medication, with subsequent medications focusing mostly on the cardiovascular system. Approved by the FDA in 2004, Prialt is one of six drugs derived from venom proteins that were currently approved for use in the United States.

Zoltan Takacs, a pharmacologist and founder of the World Toxin Bank, has spent much of his adult life attempting to unlock the key behind venom's potency, sometimes getting bit or stung in the process. Over millions of years, animal venom has evolved to reach specific pathways quickly, often affecting the cardiovascular or nervous systems in an animal's prey. By harnessing these same proteins within the venom, scientists are working to target these pathways for therapeutic reasons.

"Think of it, the very survival of the viper in the Sahara is dependent on its toxins," said Takacs. "For sure nature made them darn good. Literally, evolution has done half of the work for drug development."

With the "magician's cone" snail, the toxins contained within the venom have the ability to target specific channels within the cell that deal with pain.

Bingham said some pain medications were akin to a "skeleton key, which opens multiple locks," meaning the medications address the ailment but also cause side effects. Prialt taps only specific channels, lessening the chances of side effects.

"As pharmaceutical chemists, we want to redesign a key and be able to pick a lock with extreme specificity," said Bingham. "These specific keys that allow us to hit specific locks. We can only learn from them."

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