Sea Snail Toxin Offers Promise For Pain

Khyber writes to tell us about research out of Australia that holds out hope for chronic pain sufferers. The toxin of a sea snail, called conotoxin, has a component that has been shown to directly target pain receptors in experimental animals. Unlike essentially all existing pain relievers, conotoxin seems to suppress pain without side effects. Human trials are a year away.

Comments

Re:Toxin...Toxic?

[bensafrickingenius]

Wouldn't be the first time we've used a toxin in non-toxic ways. Botox (botulism toxin), anyone? I'm sure it hurts like hell if you're *stung* with the toxin, but has no such effect when ingested. (or something).

Before anyone else chimes in..

[Khyber]

It's not the toxin itself, rather a component of the toxin that offers the pain relief. The /. editors must've edited that out, from my original entry.

Elan already has a Conotixin on the market

[Anonymous Coward]

Irish biotechnology company Elan Pharmaceuticals markets the first commercial conotoxin analgesic, ziconotide (Prialt), for intractable nerve pain. It is from the omega-conotoxin family, one of five major families of conotoxins.

http://www.theage.com.au/news/creative--media/pain killer-comes-out-of-its-shell/2005/07/24/112214372 8598.html

Re:Toxin...Toxic?

[MrLogic17]

Yes, but not the reason you think.

http://en.wikipedia.org/wiki/Nehushtan
Numbers 21:4-9

(Pardon the King James, couldn't find a modern transation in short order)

21.6. And the Lord sent fiery serpents among the people, and they bit the people; and much people of Israel died. 7. Therefore the people came to Moses, and said, We have sinned, for we have spoken against the Lord, and against thee; pray unto the Lord, that he take away the serpents from us. And Moses prayed for the people. 8. And the Lord said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live. 9. And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.

Different from ziconotide?

[Wilson_6500]

There's already an anesthetic drug out there that's based off of a conotoxin. Ziconotide, from what I can tell, is a synthetic conotoxin substance based upon omega-conotoxin derived from the cone snail. Wikipedia has an entry on it, including that it's already in use as the drug "Prialt."

I don't understand why nothing in the article even mentions this already-existing drug derived from (probably different) conotoxins.

At least one conotoxin already commercialized.

[Vellmont]

A brief look at Wikipedia indicates there's already a commercially available drug derived from conotoxin that provides relief from pain:

-conotoxin inhibits N-type voltage-dependent calcium channels. Because N-type voltage-dependent calcium channels are related to algesia (sensitivity to pain) in the nervous system, -conotoxin has an analgesic effect: the effect of -conotoxin M VII A is 100 to 1000 times that of morphine. Therefore -conotoxin M VII A is used as an analgesic drug named ziconotide; it is marketed under the brand name Prialt®.

Presumably this is a different component of conotoxin.

Re:At least one conotoxin already commercialized.

[alkaloids]

Right. The article is horrendously vague, though I guess it has to be. "Conotoxin" is the name of actually a family of different compounds (small peptides) that tend to interact with ion channels. Ion channels are the proteins in neurons that basically transmit electrical information from one end of a neuron to the other. So if you can clog up ion channels, you can stop information transfer - including pain information. There are lots of ion channel types, and lots of different ion channel blockers and it's long been one of the promises of understanding ion channels that if we can block specific ones with high potency and specificity we'll be able to stop pain. The hope is that you'd be able to block the channels involved in transmitting information about pain, but not interfere with the channels that transmit signals from the brain to the muscles. This is all similar to how drugs like lidocaine work where they will 'break' an ion channel for awhile and so you can't feel pain from those neurons. However, this is different from other pain treatments which function by changing your perception of pain (things like morphine or other opiates).

So anyway, that's why toxins can be used to treat pain. The earlier drugs developed were (omega)-conotoxins, which tend to target the voltage-dependent calcium channels. This is from the (mu-O)-conotoxins which is a different family that tends to block the voltage-gated sodium channel, which is actually the channel I've done most of my PhD research on. In fact, I was in the process of writing a research proposal to do pretty much what the experimenters in this study have done. It looks really interesting, but there are still tons of problems involved in using peptides therapeutically (your digestive system tends to be remarkably good at tearing peptides to bits, for example). Oh well, you can't win 'em all.

Re:Toxin...Toxic?

[torako]

While your Bible citation applies too, most people would say that the Rod of Asclepius is a symbol of Greek mythology (probably older than your Bible text) Wikipedia text: http://en.wikipedia.org/wiki/Rod_of_Asclepius The summary says:

The Rod of Asclepius is an ancient Greek symbol associated with astrology and healing the sick with medicine. It consists of a serpent entwined around a staff. Asclepius, the son of Apollo, was practitioner of medicine in ancient Greek mythology. He was instructed in medicine by the centaur Chiron also connected to the constellation Ophiuchus.

Re:Toxin...Toxic?

[Hatta]

It's all in the dosage. *ANYTHING* (even, say oxygen or water) is toxic if given in a high enough dose.

Including ethanol, nicotine and caffeine to name a few.

With the notable exception of THC, the active ingredient in marijuana. There has never been a single fatal case of THC poisoning in all of medical history.

Pain medication

[XNormal]

Aspirin, ibuprofen (Advil), etc are anti-inflammatory drugs. They block the body's response to provocations which is often what causes most of the pain. They all have the unfortunate side effect of irritating the stomach lining and increasing the chances of getting an ulcer. Nobody really knows how many (mostly elderly) people die from internal bleeding caused by these drugs every year.

Opiates affect the way the brain perceives pain. They work great and are relatively safe - but addictive. Some people find them pleasurable but most people don't really enjoy the experience. Both groups can become addicted if they use them often enough. The first group is simply more likely to do so for non-medical reasons.

Nobody is really sure how acetaminophen (Tylenol) actually works. It appears to be a variant on anti-inflammatory drugs with fewer side effects but it may also have some direct effect on the brain. It's safe and effective for minor pains but its usefulness is limited for severe pain because larger doses are toxic to the liver. This one also kills many people every year who don't take the warnings seriously. Many of the victims are children.

A new drug that affects the pain receptors directly could be a welcome addition to this arsenal.