Seroquel will diminish the effects of DOC but will not stop it from working completely. It will still work, just not as well and increasing the dose helps but it still won't be as good as DOC without seroquel. When I've taken seroquel, I stop it for a few days before tripping to minimize any effects from the seroquel but this may be a bad idea - how bad depends on why you are taking it and how you generally manage if you skip days along with how mentally stable you were before starting seroquel and maybe now as well since you may have improved.
You probably should not stop the seroquel if you have schizophrenia and if bipolar, make sure you are not in a manic episode. Depression is probably not as big a deal if you feel that and for me, DOC can alleviate depression but be careful and make some notes of how your mood changes from a few days before stopping until a week or so after the trip every day in a journal if you want to take my advice (which I never followed, but I have been reckless and careless with drug use and anyone who pays attention to my posts knows that). Don't emulate my bad behavior. But this is something I never thought of doing and I would guess most others would not think to do this and make a mood chart either.
