Obscure and Unknown: 2-MDP

*WARNING* The substances mentioned in this series have little to no record of human use, and thus the effects they have on humans are either poorly understood or entirely unknown. Much of what this information is simply hypotheses based on animal trials or very small human sample sizes. Very little information exists about their acute or long-term toxicity. Under no circumstances should any of these substances be ingested by a human outside of a clinical setting where psychological and physiological effects can be closely monitored and extremely precise doses can be prepared and TITRATED. DO NOT seek any of these out if you do not have access to those resources.

Hello, this is next in a series I started with one entry years ago and never got back to. I'm back at it now. With New Frontiers I hope to delve into the potential of extremely little-known drugs (Only looking into hallucinogens for now sorry)- many are simply novel chemicals with little studies having been done so far. Others existed as candidates for pharmaceuticals but were aborted during clinical trials due to the sort of side effects that I am specifically seeking. Others are simply understood to be hallucinogenic and have been for a while, but for one reason or another have just been neglected for study. Hopefully by delving into these, it can shed light on potential base structures for producing analogues that may produce more useful and desirable effects relative to the known substances. There seems to truly be no upper bound on the variety of psychoactive substances.
Today's hallucinogen will be:

2-MDP

2-MDP is an NMDA antagonist and a dissociative anesthetic. It bears a passing resemblance to a variety of anticholinergic deliriants, though it is decidedly a dissociative, with an α-methyl side chain negating all anticholinergic effects1,3. The first mention of this chemical was a 1966 annual report on medical chemistry, where it is listed as a potential CNS stimulant1. In the early 1980's, the role of NMDA antagonists in producing a state of dissociative anesthesia was definitively cataloged, characterized by the standards of PCP, Ketamine, and MK-801. It was in the mid 1980's that several studies were done to establish 2-MDP as an NMDA antagonist and determine potential medical uses, either as an anesthetic or an anticonvulsant2,3,4. It was ultimately abandoned for the "PCP-like" behavioral effects observed in animal test subjects  and limited medical effects and was never officially tested on humans2,3,4.

Most discussion will be about the (-) isomer, which was initially demonstrated to be more potent than the (+) isomer in terms of receptor activity2. Later studies determined the (+) isomer was inactive as far as anesthetic and psychoactive or behavioral effects3.

Only one study delved into the psychoactive effects of 2-MDP, "Phencyclidine-Like Behavioral Effects of 2-Methyl-3,3-diphenyl-3-propanolamine (2-MDP)", by Tang, et al. Behavioral effects were characterized for rats and rhesus monkeys through observation and performance in a series of tests. Test performance in the rats very closely mimicked that observed for PCP, and it can be extrapolated that similar effects may be observed in humans.
Meanwhile, the effects of attempted anesthetic doses in monkeys showed:
"After a 1 mg/kg dose, there was calmness, ptosis, salivation and reduced spontaneous movements. Additional doses up to a total of 5 mg/kg produced a cataleptic state with weak responses to manipulation. Most of the overt effects disappeared six hours after the injections."
The triggering of a catatonic state recalls the "hole" experience of high doses of dissociatives.

Indeed, doses of dissociatives intended for total anesthesia are significantly higher than doses used recreationally. Based on the primate trials, a "recreational" psychoactive dose (in other words, a non-full anesthetic) on a human is indicated to be in the >1 mg range, meaning this would be easier to dose than some research-only dissociatives that dose in the μg range (CNS-5161, MK-801, 8A-PDHQ, PD-137889 etc). The initial study indicates it has stimulant properties at 1/3 an equivalent dose of amphetamine, perhaps placing a low-end dose at ~10-20 mg1. However, this cannot truly be known for sure until trial are attempted in humans, and as of now it would likely be highly unsafe to do this outside of a clinical setting.

There's no telling what the unique features and subtleties of a dissociative experience from this chemical would be in humans. Only somatic and physiological effects have been observed in other animals. Close to nothing is known about its toxicity either acutely or chronically. It is at least less likely to induce seizures than PCP at extreme doses4. An extreme dose of 100 mg/kg was demonstrated as lethal, though it is unknown how close this is to a lower range of a lethal dose4.

Also very interesting was a note that at the very least, stimulant effects were observed in cats and dogs for up to 24 hours1. Dissociative anesthetic effects were noted to have faded in about 6 hours in monkeys3. Thus, this indicates that this substance may yield a very long lasting experience, with the dissociative component presenting for around 6 hours and a long stimulating afterglow. Once again, how this would present specifically in humans is still unknown.

Because of the unique chemical structure it is hard to extrapolate a safety profile from known dissociatives. This is one that should be absolutely approached with caution.

Sources and Further reading:
1-John H Biel. Annual Reports in Medicinal Chemistry, Volume 2. Academic Press 1966. p18
2-Blake JC, Davies SN, Church J, Martin D, Lodge D. 2-Methyl-3,3-diphenyl-3-propanolamine (2-MDP) selectively antagonises N-methyl-aspartate (NMA). Pharmacology Biochemistry and Behavior. 1986 Jan;24(1):23-5.
3-Tang AH, Cangelosi AA, Code RA, Franklin SR. Phencyclidine-like behavioral effects of 2-methyl-3,3-diphenyl-3-propanolamine (2-MDP). Pharmacology Biochemistry and Behavior. 1984 Feb;20(2):209-13.
4- Hayes BA, Balster RL Anticonvulsant properties of Phencyclidine-Like drugs in Mice Eur J Pharmacol. 1985 Oct 29;117(1):121-5.