Hey Peyote:
First of all re-read my post. I did not specify neurotoxicity in humans. Secondly, and more importantly don't be so quick to argue a drug's supposed "Saftey" profile, when your only argument is that it has not yet been "Proven" to be neurotoxic in humans. It is not good science, nor is it an intelligent approach to the study/use of any neurologically active agent.
What I had typed above was roughly paraphrased from an informative commentary titled: "The Discociative FAQ" which was once available on the Lycaeum (Before its demise - If anyone has a copy of this, or a working link to a new source, I would greatly appreciate it.) This work addressed he legitimate concerns inherent with the use of disociatives as well as giving a fairly balanced summation of what we presently do and do not know about these agents.
True, we have not yet seen Olney's lesions in Humans. However, we have done so in mice, rabbits and a number of other mammals. Have we detected neurotoxicity with Ketamine's closest relatives in humans? Absolutely. PCP, DXM as well as other more obscure chemically related molecules have all demonstrated this. I ask you, is this "Proof" that ketamine is SAFE, and that it DOES NOT posess neurotoxic potential at any does or duration? Let's not jump to embrace a conclusion, and certainly not to the one which we, as people who enjoy the use of discociatives would prefer.
All to often I hear people trying to argue that virtually every illicit drug is "Safe", simply because they have found one little tidbit of info that they can cling onto... I have heard this with E, K, Heroin, Meth, etc. Don't fall into a trap of believing what you want to believe, verses what potentially could be the truth.
As far as the Primate studies which you mentioned briefly, let me cast a bit more light on them. These studies were conducted in part by Dr. Frank Sharp and also by one of Dr. Olney's colleagues, Dr. Nuri Farber. We know little about these studies, simply because they are UNPUBLISHED. We do know that they did not show proof of toxic changes in a group of monkeys up to 10mg/kg when administered intramuscularly. In his own words Dr. Farber concluded: " ...the methods used in the (Ketamine) monkey studies so far are unsatisfactory, because the animals were probably too young". (Bare in mind that the neurotoxic effects seen in rats were seen only in Adult rats) Dr. Sharp himself also refused to give the drug a clean bill of health, as the pharmaceutical company refused to publish their own primate studies, and work on older monkeys was not pursued.
The question of how you choose to quantify "Neurotoxicity" also needs to be addressed. Just because brain tissue might not be directly damaged, doesn't mean there cannot exsist other negative pressures on how the brain functions. There is evidence that the brain may actually be "Rewiring" or "Dewiring" itself through discociative use, and that this may at least be partially responsible for the negative symptoms and memory loss that have been documented.
I am going to provide on last quote from Dr. Karl Jensen M.D., Ph.D. a researcher and clinician who is currently working with MAPS, and is regarded as the one of the world's leading experts on Ketamine. I feel it sums up subject quite nicely:
"The branches and junctions of adult neurons undergo many changes throughout life. This is like a tree growing new buds. N-P receptors are involved in these structural changes ("plasticity"). which could form the basis for some types of long-term memory, and of the brain's attempt to compensate for aging." He goes on to state: "Some persistant memory difficulties after prolonged use of ketamine may be due to a molecular change withing cells. The failure to see, through a microscope, dead cells, damage to areas inside cells, or damaged nerve terminals in drug toxicity studies is NOT necessarily evidence of a lack of persistent change in the "wetware" of the brain."
Fact: THe use of Ketamine has been clinically linked with a wide range of unpleasant mental effects. This list includes: Anxiety, memory loss, panic attacks, post-traumatic stress disorder, persistant perceptual changes, mania, paranoia, delusions of granduer and association.. the list goes on. We might not have the entire ketamine puzzle put together yet, but we do know that its use can and does manifest serious ill neurological effects that should not be downplayed or ignored.
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"I dislike the drug you are using, but I would defend with my life your right to use it."
- Paraphrase on Voltaire
"He who makes a beast of himself gets rid of the pain of being a man."
- Dr. Johnson
"We do not sense imagination enough to sense what we are missing."
-Jean Toomer