Maybe somebody can help shed some light on something that happened to me two days ago...
I've been taking roughly 60 mg pure DXM HBr diluted in water every two-three days for a couple of weeks now, mainly for depression. It's been helping. Two of these times I took 125 mg without any undesirable effects.
So two days back, I had a morning dose of 60 mg and was quite happy and stimulated all day long, the usual effects in other words. Feeling as good as I was, I decided it was time to try a higher dose, something I've been planning for a while but never got around to thanks to non-optimal conditions. At 8:00 pm I dosed myself with 250 mg right before a meal. By 9:00 pm this second dose was coming up fast (right on time).
But this time the high wasn't good. It was dysphoric, my emotions were severely blunted, there were very few visuals, and my imagination was hardly enhanced compared to previous trips. I've had similar effects from syrup in the past, but never to this degree of unpleasantness

On the plus side, I felt more dissociated from my body than normal. I was barely receiving input from my limbs.
There are only two factors I can think of that would cause this sort of reaction: 1) this was my fist time using pure DXM powder at this dosage; 2) I took a small amount of DXM earlier in the day. So I can only figure that it had something to do with the DXM/DXO balance of the high.
Theoretically, my initial 60 mg dose might have used up enzymes needed to break the DXM down into DXO, thus resulting in a higher DXM/DXO ratio, right? Does this account for the effects I experienced? If not, how might I prevent this from occurring again (aside from not doing DXM)? I don't have any PEG laying around, so could I prepare my gut with glycerine or something to help aid absorption?