Re: An Introduction to our Psychedelic Medicine, Research & Microdosing Forum

This paper is a hypothesis-generating review, not a clinical study, and it provides no direct evidence that microdosing psychedelics causes cardiac valvulopathy in humans. Its central argument rests on the observation that LSD and psilocybin share 5-HT2BR agonist activity with drugs like pergolide and fenfluramine that are known to cause valvular heart disease. But 5-HT2BR agonism is not itself a sufficient cause of VHD, and the paper's own data demonstrates this: ropinirole and lorcaserin are both 5-HT2BR agonists with no VHD association whatsoever. The authors' attempt to rescue the hypothesis by invoking a 15 nM binding affinity threshold is undermined by norfenfluramine, which causes VHD at a Ki of 52 nM, well outside their proposed cutoff. The logical structure of the argument is essentially: these substances share a receptor-level property with known cardiotoxins, therefore they may share the same risk. That reasoning alone proves nothing. More critically, the paper never seriously addresses dose-response or cumulative exposure, which are the variables that actually matter. The drugs implicated in VHD were taken daily or near-daily for months to years. A typical microdosing regimen involves sub-threshold doses two to four times per week, with plasma concentrations that fall to undetectable levels within hours. The cumulative receptor occupancy burden is categorically different from the comparator drugs, and no attempt is made to quantify that gap. The authors themselves acknowledge that no controlled studies have assessed VHD risk in microdosers, and that the existing microdosing research literature spans weeks rather than the years over which VHD develops. Sharing this paper as evidence that microdosing is dangerous to your heart is a significant misrepresentation of what it actually concludes.