Ketamine, Memantine, Dextromethorphan etc etc

[mforce00]

Has anyone here taken Ketamine, Memantine, Dextromethorphan, or any other NMDA receptor antagonist for pain?
I've been reading up on NMDA and how it effects opioid tolerance and chronic pain. I'm not too sure how NMDA antagonists are prescribed... and if doctors will even do it due to the sides.

[mrsdoubtfyre]

Our PN board in the past had some discussions on these interventions.

1) Memantine was not popular. Its use for pain is secondary to the indication for cognitive use. I don't believe the FDA approved it here for pain/PN. But it was in use in Europe for this indication, before it came here. If you search PubMed using this keyword memantine neuropathy
you will find papers demonstrating poor pain results

2) Dextromethorphan-- Nide44 at PN tried this with his doctor. He was not
happy with it. You could PM him for details.

3) There were ketamine posts on this board when it first appeared in Oct 06.
Some pain papers I have read discuss possible oral forms coming in the future.
Here is another example:
J Pain Palliat Care Pharmacother. 2002;16(3):27-35. Links
Ketamine as an analgesic: parenteral, oral, rectal, subcutaneous, transdermal and intranasal administration.

* Kronenberg RH.

Thunderbird Samaritan Medical Center, Glendale, AZ 85306, USA. rhkrph@aol.com

Ketamine is a parenteral anesthetic agent that provides analgesic activity at sub-anesthetic doses. It is an N-methyl-D-aspartate (NMDA) receptor antagonist with opioid receptor activity. Controlled studies and case reports on ketamine demonstrate efficacy in neuropathic and nociceptive pain. Because ketamine is a phencyclidine analogue, it has some of the psychological adverse effects found with that hallucinogen, especially in adults. Therefore, ketamine is not routinely used as an anesthetic in adult patients. It is a frequently used veterinary anesthetic, and is used more frequently in children than in adults. The psychotomimetic effects have prompted the DEA to classify ketamine as a Schedule III Controlled Substance. A review of the literature documents the analgesic use of ketamine by anesthesiologists and pain specialists in patients who have been refractory to standard analgesic medication regimens. Most reports demonstrate no or mild psychotomimetic effects when ketamine is dosed at sub-anesthetic doses. Patients who respond to ketamine tend to demonstrate dramatic pain relief that obviates the desire to stop treatment due to psychotomimetic effects (including hallucinations and extracorporeal experiences). Ketamine is approved by the FDA for intravenous and intramuscular administration. Use of this drug by the oral, intranasal, transdermal, rectal, and subcutaneous routes has been reported with analgesic efficacy in treating nociceptive and neuropathic pain. Ketamine also has been reported to produce opioid dose sparing and good patient acceptance. A transdermal formulation is currently under patent review in Brazil and an intranasal formulation is currently undergoing phase I/II clinical trials.

PMID: 14640353 [PubMed - indexed for MEDLINE]

The problem with ketamine is that it is still rather experimental and finding a doctor to give it is difficult.

Magnesium remains a simple mineral to block NMDA receptors. I have a magnesium thread here on the vitamin forum.
It can work for you, if you are one of the commonly deficient in this country.
http://www.answers.com/topic/nmda-receptor

[oh_snap]

A very smart anesthesiologist used ketamine to control severe, unexpected post-surgical pain (had suffered a nerve injury during the surgery).

He had tried all kinds of "more" opiates, and nothing worked. My blood pressure was 200 over something, and it felt like I had been cut in half by a torch. When he figured out that this was very severe neuropathic pain, he tried the ketamine. I was very lucky that he was there...as the nurses and other docs had no idea what to do, and felt I was just being a weenie.

It was quite effective. I have used it in compounded form and it was also effective.

[mforce00]

Do you currently take Ketamine? Is it given in tablets to humans? I could only find information on vets given animals Ketamine in pill form.

[oh_snap]

mforc
I do not take ketamine. I take keppra for neuropathic pain.

Ketamine does have a use outside of vets, and street abuse and what Ms. Doubtfyre posted is right on.

I think that ketamine gets a negative rap because of abusers breaking into vet offices, and either using it (tripping out), or selling it on the street.

I think it is a med that could help many (with neuropathic pain), used in the right hands. I did not suffer any of the negative side effects of its use, and mercifully found relief from a level of pain/burning I could never have ever imagined, and had never experienced until then, and I have also had a couple of spinal surgeries.

Again, I think it is a good med but already has a bad rap, but it is clear that anesthesiologists understand it effectiveness, and have the ability to use it without significant side effects.

The fact that it is also a street drug (special K) will probably keep its use from ever becoming widespread, or mainstream, unfortunately.

If anything, it is interesting how it works, and may be other meds will be developed like it, and without all the negative connotations.