Ziconotide is a foreign made drug with orphan status for opium refractory pain.
The first clinical studies on ziconotide are beginning to appear. See for example, Klotz U.Int J Clin Pharmacol Ther. 2006 Oct;44(10):478-83.”Ziconotide–a novel neuron-specific calcium channel blocker for the intrathecal treatment of severe chronic pain–a short review.”–from Heidelberg.
Ziconotide, taken from a marine toxin in snails, must be injected intrathecally (into the spinal fluid) and each dose runs around 3000 dollars. However, it does appear to block the N type calcium channel, which is what is needed to get the job done to stop pain. It also has side effects; namely, dizziness, nausea, and confusion. The side effects are claimed to be minimized by starting the dose slowly and working up gradually.
What is very encouraging is that it appears to stop neuropathic pain. No specific studies on central pain are yet in the literature. If it were just a little cheaper (it is manufactured in Ireland), we would have larger patient series to have more definite information on central pain. However, it probably works. If Bill Gates or Warren Buffett gets Central Pain, this will ptobably be their drug of choice.
Perhaps the most encouraging aspect is that blocking N type Calcium channels actually works. This validates the theory behind existing data on the behavior of N type channels in causing chronic pain. When the ion channels don’t work, the sodium/calcium exchange channels won’t work and hence the action potentials in pain nerves won’t fire. If Bono shows up to demand drug companies make the stuff affordable, we may be in fat city. Other N type calcium channel blockers are being developed. Someone is going to make a lot of money if they can find an oral one that works. Newron is working on just such a drug.
Although there are still no published clinical studies on ziconotide and central pain, we have had very limited feedback via the internet from CP subjects. This information unfortunately does not allow us to conclude that ziconotide is the magic cure. However, the Australians have found that the cone snail (Conus Regis) and others are a literal storehouse of medicines against pain, pharmacologic gold rush. There may yet appear other toxins which stop central pain. There are certainly a burgeoning number of snail species found to have neurotoxins which are effective against peripheral nerve injury pain. A very major problem is that the shells of these toxic snails are quite beautiful and a favorite with tourists and collectors. We recommend an immediate ban on catching or selling these snails, since their numbers are dwindling rapidly and the potential for medicines is literally exploding, with some snail varieties having as many as four hundred chemicals in their injectate which are active against pain. This is valuable not only for direct pain relief, but tagging the toxins as they interact in the pain chemical pathway will tell us what the pathway really is. We know parts of the chemical pain cascade, but we have not yet mastered all of it. Scientists have quit killing the snails, and have begun the rather dangerous approach of milking them. Of course, should the snail manage to harpoon them with its proboscis, the researcher might die.