As said before this is unsubstantiated .
This has been discussed . Prokinetic effects . Quetiapine effective dosage depends on age, weight, condition etc . It's wrong to say you need "high dosages" . No evidence of that .
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It is clear that a single big dose is bad .
Whether it's more effective or not , do not suggest such practice .
I'm going to respectfully disagree and say that the reference I link to in my post is from what I can tell the most definitive source of information on the topic that has appeared anywhere on this forum. I consider that source to be substantiated, more so than the personal opinions or anecdotal evidence of any single forum member (including myself) and their own unique experiences with or personal opinions of dosages.
Like most medications Quetiapine's effective dosage for the intended (psychiatric) purposes can vary as a factor of age, weight and the particular psychiatric condition targeted. However, what is a largely an unintentional purpose (the antiemetic effects) could still conceivably have a reliable dose threshold at which those effects appear, and this can be largely irregardless of individual differences.
A single dose of 300-400mg Quetiapine (which is not a 'big' dose by any means) is only 'bad' to the extent that [a] an isolated one-off dose not taken as part of regular routine dosage may not provide the antiemetic effects that comes from a more regularly-taken dosage of 300-400mg, a sudden starting dosage rather than gradual titration may cause more severe or uncomfortable variations of the normal side-effects of the medication or [c] it may sedate you too quickly that you do not complete the rest of the SN protocol.
Although I stand by my opinion that Quetapine dosages for antiemetic effects is a bit of a nebulous unknown on this board, I think one thing that is fairly obvious is that this complexity means that it is probably not something you would want to start using, either routinely or as a once-off, purely for the purposes of the SN protocol. Especially if other suitable antiemetic drugs are available to you (depending on country of residence) those are far more straightforward. The only people for whom this current topic is relevant are those who are already on Quetapine for psychiatric purposes, but are unsure whether their current dosage is sufficient for antiemetic effects. For those individuals, I would suggest that the resource I linked to is still the most reliable, albeit rare, figure to go on.