Caffeine and antipsychotics

[Bex x]

I'm doing my psych bit at the moment, and a patient of mine who's on Quetiapine said that he isn't allowed caffeine, because that'd undo the antipsychotic effect of the meds. I can see how it could counteract the sedative effect, but does it actually make the drug less effective against psychosis? If so, how does it do it?

[Yixian]

Well.. many antipsychotics compete for the same metabolic enzymes as caffeine does, but this increase the serum concentration of the drug so you'd think that it would make the antipsychotic more or too effective.

Caffeine increases the elimination time for Clozapine for eg. maybe there are some atypicals though which have a different interaction.