Grapefruit juice contains compounds called furancoumarins which bind to enzymes of the Cytochrome p450 class, particularly CYP3A4, and inhibits its effects.So, any drugs requiring this enzyme to be metabolized will be broken down less with more drug being absorbed causing higher blood levels and risk of toxicity.
Harmala alkaloids have variable effects on the different subclasses of the CYP450 system and increases the gene expression of some subclasses (including CYP3A4) and reduces others.DMT doesnt get metabolised by this enzyme system so I dont think taking grapefruit juice with DMT alone would have significant effects one way or the other.
Harmala alkaloids are metabolised by the CYP enzyme system and the natural endogenous B carbolines are metabolised by the CYP enzyme subsets 1A2 and 1A1 but interestingly harmala alkaloids actually increase the gene expression of CYP1A2 so theoretically taking harmalas could be 'self-limiting' as it induces the enzyme which actually metabolises it.The furancoumarins in grapefruit juice have an inhibitory effect on CYP1A2 but less than with CYP3A4 so conceivably this could enhance the effects of the harmala alkaloids if taken together.
Cimetidine inhibits CYP2D6 and CYP3A subclasses, so again it can inhibit the enzyme subclasses induced by the harmala alkaloids but has no significant interaction with the subclasses required to process the harmala alkaloids.
Makes sense?:idea:
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