ecstacylover
Bluelighter
There's been no documented arrhythmias occurring due to a single oral dose of ondansetron (according to this 2014 review), so if you use it definitely stick to that protocol. The 5-HT3 affinity of ondansetron (Ki 1.6nM) is much higher than its hERG affinity (IC50 810nM), suggesting that there is a bit of wiggle room.Right, there are some I would definitely avoid taking in combination with Ondansetron like Ibogaine or the NBOMe’s for example
Of the arrhythmias which have happened in the presence of ondansetron, 80% of them used IV admin and 67% were in the presence of other QT-prolonging drugs.
Also I kind of doubt that psychedelics are exerting cardiotoxic effects through open-channel hERG block, because their affinity there is very low. For example, the hERG IC50s for 25D-nBOME, 4-AcO-DET, 4-HO-MET, and 4-HO-DMT are 5,800nM, 14,400nM, 37,500nM, and 55,000nM, respectively. Yet a 25mg dose of 4-HO-DMT, on average, only reaches peak serum concentrations of about 100nM. In cases where psychedelics are prolonging the QT interval, my guess is that it's due to activation of serotonin receptors within cardiomyocytes. The ion channels mediating ventricular depolarization are lipid-gated, and PIP2 depletion from over-activation of 5-HT2A could in theory produce rundown of the activity of these channels.
Actually it seems riskier to combine psychedelics with ketanserin (hERG IC50 110nM) than with ondansetron, but a number of studies in humans have pulled this off without any issues.