John Claude Krusz, Ph.D., M.D.
ANODYNE Headache and PainCare
5446 Glen Lakes Drive
Dallas, TX 75231
214-750-6664
http://anodynepaincare.org/Clinic_Staff.htm
Transcript: How Ketamine & Lidocaine block neuropathic pain
Another exciting avenue for treatment, at least in my clinic, is using intravenous therapy methods. Part of the practice is set-up like an emergency room so if you have a flare up of headache, pain, etc., you give us a “heads up” and we’ll bring you in and put an IV line in and treat you. We have been using two or three anesthetic agents in low dosages to block neuropathic pain.
There’s an exciting new molecule. It’s actually not new because it’s been around for forty years but it is an anesthetic agent that sometimes still gets used in cardiology surgery and certainly a lot of veterinary use. It’s called Ketamine. We use it in sub-anesthetic doses so nobody falls asleep, nobody’s anesthetized.
Ketamine has a unique property to block neuropathic pain signaling by blocking one of the worst transmitters that promote pain called glutamate and it’s a specific glutamate inhibitor which can often not only block pain. But also the second property of Ketamine is that it can undue the tolerance that develops due to opioid analgesics like Morphine, Oxycodone, and Hydrocodone so that people that are chronically on pain meds find that their pain meds don’t work as well as they did because of tolerance. Ketamine has an unusual property to undue some of that tolerance so that lower doses might be more effective.
Now it’s been an exciting new medication. We have tried it IV. We’ve published on it. We’re looking at it intra-muscularly in cases where we can’t get an IV line in but IV does work better. In a small number of patients, we are beginning to use compounded oral Ketamine to see if we can maintain a better response. Now this is all exciting work with one agent.
Another agent that’s been out there for a long time, used by dentists certainly and lots of physicians for nerve blocks – Lidocaine. It’s a local anesthetic. Again not used in anesthetizing doses but in very low doses it blocks another item that gives build up in neuropathic pain. For instance, it blocks sodium channels which we know that in neuropathic pain syndromes, sodium channels are over-expressed and there is too much sodium channel activity allowing too much electrical activity to fire back to the brain. You can block that with Lidocaine successfully. Then you can open the door to not only having pain relief from a flare up on a given day or a given week but sometimes you get a multi-day affect with these medications and the best news is that you can then return back to our neuronal stabilizing agent group and pick a medication that has properties that mimic either Ketamine or Lidocaine.
So, if Lidocaine works, you have four choices. You’ve got Topomax. You’ve got Lamictal. You’ve got Zonegran and you’ve got Trileptal and Tegretol actually – five.
If Ketamine works successfully, you have an agent called Topomax which has dual affects and you also have a medication officially approved for other uses called Namenda which specifically blocks the same glutamate receptor.
So, it’s not only a treatment but it can be a probe for figuring out what direction to go in for oral medication suppression of pain.