Seroquel blocks several types of receptors, including ones affecting Dopamine, Norepinephrine, and Serotonin. Studies show that since [unlike many other antipsychotics] it quickly stops blocking dopamine receptors, it allows for dopamine levels to restore more quickly, making it less likely to cause the side affects associated with other antipsychotics.

As for how thas applies to this thread, psychedelics act mainly on the Serotonin receptors (although LSD acts on the other two as well), and so taking seroquel will not allow the psychedelic to interact with said receptors anymore, thus ending the trip.

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To the OP, according to Dr. Stanislav Grof, stopping LSD with antipsychotics can "freeze" whatever it is that you were trying to fight in your subconscious. He is not perfect though, and might be wrong about that point.

In any case, I would personally only use antipsychotics to abort a trip if the person involved became a danger to themselves or to others. Otherwise, a benzo works just fine, if not better (since it allows you to work through whatever it is you were scared of without fear)

In 5 days I get my hands on some LSD, is it safe to do while I take 25mg of seroquel, an extremely low dose every night?