Dextrorphan (abbreviated DXO
) is a dissociative anaesthetic
used to block NMDA
receptors. It may be administered following stroke
to reduce metabolism and prevent ischemic brain damage
. It is also used in to detect PCP receptors
Non-medical drug users will encounter DXO as the primary human metabolite
, or DXM
. It is created when the liver enzyme cytochrome P450
(also called CYP2D6
or debrisoquine 4-hydroxylase
) removes the methyl group at position 6 of the DXM molecule.
The quantities of DXM found in a regular dose
of cough medication (~15mg) evidently do not produce active quantities of DXO. However, when DXM is consumed in recreational
doses (100mg and up), large amounts of DXO are also created. DXO has dissociative
effects, which some liken to those of marijuana
. These effects are thought to soften some of the more bizarre and intense effects of DXM, and indeed people who have low levels of cytochrome P450 tend to have more disturbing (and longer) trips.
The amount of DXO relative to DXM can be decreased by dividing one's dose (because another DXM metabolite, 3-methoxymorphinan, blocks cytochrome P450), or by injecting DXM subcutaneously.
All information except the first paragraph extracted from William White's DXM FAQ, the most impressive piece of lay scholarship I've ever seen.