!!! Super DXM !!! Very interesting.

[eche05]

Abstract: Antihistamines dramatically pronounce the effects of DXM.

Okay, everybody [who read a decient ammount about dextromethorphan HBr] is aware of the effect of grapefruit juice on the intensity of dextromethorphan. This effect is from the bergamottin inhibitory effects on cytochrome P450. If anyone has compared the "trip" of coricidin (containing Chlorpheniramine Maleate) versus 'straight' DXM, the individual will describe the Coricidin experience as 'more intense', 'clouded' or a less favored description 'dirty'. Chlorpheniramine Maleate is a well known antihistamine and effects the production of Acetylcholine in the brain, which could attribute to the mental cloudiness associated with most antihistamines. What is unknown, however, is that Chlorpheniramine Maleate, among the majorty of antihistamines (including piperazine and its derivitives) are also a cytochrome P450 inhibitor! Substrate of CYP2D6 [cytochrome P450] (moderate), 3A4 (major); Inhibits CYP2D6 (weak).



Meaning not only does CPM effect mental cognizance, it antagonizes the oxidation of dextromethorphan into dextrophan, which [both] are potent N-methyl d-asparate receptor (NMDA R) antagonists, producing what the user describes as the 'high'.

SWIM, upon this realization of H1 receptor antagonists (which recently discovered to inhibit cytochrome P450 functioning) decided to test this theory with a hydroxyzine-relative, cetirizine (Zyrtex).

Experiment A 600mg of DXM, no antihistamine

600mg of DXM without antihistamine (in the form of zicam cough melts, 30mg each). No immodium was taken to counter-act the well known associated diarrhoea. No chemical anti-nausea measures were taken (laying down occured occasionally)

Objective: A randomized (though from the same lesson) series of 25 math problems were completed with 65% accuracey. [glencoe.com] (Abstract thinking is effected less so than concrete thinking due to inhibition of the motor cortex and the formal-operational frontal lobe)
Subjective: The user reported normal physiological inhibition (slowing down) of limb mobility, and sensory input (dissociative anesthesia), although perception of his sorroundings remained 'relativally normal'.

Experience B 600mg DXM, 10mg of Cetirizine (Zyrtec)

600mg of DXM with 10mg of Cetirizine HCl (in the form of zicam cough melts, and zyrtec respectively). No immodium was taken to counter-act associated diarrehea. No chemical anti-nausea [anti-emetic] measures were taken asides physical alleviation (laying down occured occasionally).

Objective: The same test was taken by the same user approximately 3 weeks later, and the results were significantly lower. 45% accuracey 2.5 hours after ingestion, and when taken a second time 4 hours after ingestion with 23% accuracey. The results were stunning to the user.
Subjective: The user reported abnormal mental cognizance of sorroundings, with a much more pernounced dreamlike quality. "...white noise is the normal auditory background, the effect is similar to visual 'white noise', i.e., visual blankets that serve to create a backgruond to contrast everything to" When moving, the user reported that there was much more resistance, and he felt that walking was more "automatic" as opposed to the more voluntary movement of the Experience A. He felt as though he were interacting with a machine - a metal, noisy, impassive, impersonal enviornment; almost like a dark factory within a dream. A "dr. Suess nightmare" What confounded me was that the user reported this was equivilent to that of only 480mg [16 pills] of Coricidin (which has a much higher dose of anti-histamines). Other users have reported on the intensity of Coricidin vs. unadultrated DXM according to Erowid.org/experiences.

Note: The user was not informed of the effects of antihistamines on dextromethorphan or associated cytochrome P450 inhibition. The user assumed it was to counter-act 'robo itch'. This was a blind study on behalf of the subject; unfortunately I couldn't get a third person to make it double blind :/

In conclusion: Antihistamines (some, if not all) severly effect the dextromethorphan experience, for better or for worse is up to the individual to decide. I strongly caution against the use of extremely high doses of CPM (which has well known negative physiological effects). I caution also against the combination of CY P450 inhibtors (laymens terms: don't combine antihistamines and grapefruit juice when taking DXM)!
????: Drugs Forum http://www.drugs-forum.com/forum/showthread.php?t=73676


Be safe, know what you're putting into your body.

-eche05

[surgery_x]

Wonderful - I loved how this was a blind study as well (too bad it wasn't double blind, but that's a stretch for clandestine studies).

Dextromethorphan is metabolzied by cytochrome P450 isozyme 2D6, as well as hydroxyzine and it's metabolties / precursors such as cetirizine and chlorphenermine melatate - makes sense it would antagonize the excretion of dissociatives at that enzymatic substrate. Good job!