I'm not sure yet as there were too many unknowns involved but I'd say that noscapine is indeed not psychoactive - on its own. You know what it does? Modulating NMDA activity.
The sigma receptor (σR), once considered a subtype of the opioid receptor, is now described as a distinct pharmacological entity. Modulation of N-methyl-d-aspartate receptor (NMDAR) functions by σR-1 ligands is well documented; however, its ...
www.ncbi.nlm.nih.gov
Sigma-1 receptors (σ-1R) are interorganelle signaling molecules, which have been implicated in synaptic plasticity, primarily by enhancing the function of N-methyl-d-aspartate receptors (NMDARs). On the other hand, excessive influx of calcium via ...
www.ncbi.nlm.nih.gov
I took the remaining 270mg yesterday, first 150mg and 2h later the remaining. Didn't notice anything but when I went out to buy some things I noticed a remarkable lowering of my usual heavy inner tension and anxiety. Went for the first long walk in ages and actually enjoyed it a bit. Now in the morning the withdrawal from kratom was barely noticeable when I usually would wake up pretty stressed.
As I've been experimenting with CBD in the last 2 days too and took 60mg DXM XR in the evening, things aren't so scientific as they should be but I'd say that it is synergistic with CBD which sounds reasonable given that both sigma agonists as CBD do some negative modulation at NMDA. The lowered withdrawal might be from the DXM but again, they will be synergistic if I'm right. 60mg XR barely touch NMDA and wouldn't even take SNRI withdrawal usually. (Intent was to take a full disso dose but as I only got one pack of pills and they registered my name etc 'for my own safety because it's addictive' - thanks, hadn't I known that you can use this stuff, now I'd, and then I didn't want to mess with my still pretty relaxed state).
I found one (non-scientific) site saying that noscapine was indeed a drug of abuse and listed effects similar to dissociatives like hallucinations, sedation, vertigo, nausea so either they used
much higher doses back then in the many gram range, don't know if this would even have an increased effect or if my dose already hit most of the receptors. Or it was combined with something else.
The mechanism is intriguing and if the relaxation was really from noscapine then it is remarkable alone - and might offer novel treatments for people with irritability / disso tolerance - but I hoped it to be stronger.
So, this calls for a new iteration I'd say.