Quetiapine is an antipsychotic, not a sedative in the same class as benzos. It has sedating properties yes, but the mechanism is different. It's unpredictable at high doses, especially when mixed with other stuff. It can cause severe hypotension, delirium, or seizures, and the sedation it provides isn't always reliable or sufficient.
If you're considering it as a substitute in the SN method, you should know it hasn't been studied in that context with any consistency. Unlike benzos, which are used specifically to reduce panic and muscle activity, quetiapine can create a confused, semi conscious state.
A typical sedative dose for quetiapine is 25–100 mg. At higher doses like 300 mg and above, the sedation deepens, but so does the risk.
If anything, it might increase the chance of vomiting or being found before the SN takes full effect. If you wanna on using it, I'd likely keep it under 400 mg, about 30–60 minutes prior. But again, it doesn't replace a benzo in function or effect.
