[Paracelsus]

SWIP is usually not just a little incredulous when experimenting with new substances/combinations, but very skeptic. That’s what I meant by saying SWIP is immune to placebo. He usually even overlooks effects like slight tiredness or slight mood lift, even if they might have been caused by the substance.

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Anyways, update on the situation. Grapefruit juice does NOT inhibit CYP2D6, but CYP3A. Many probably know this, but much more don’t. I have posted more about this here.

So since CYP2D6 remains unaffected, the metabolism of tramadol to the active O-desmethyltramadol remains the same. But less of the inactive N-desmethyltramadol and N,N-didesmethyltramadol are formed, because the responsible enzyme (CYP3A) is inhibited by grapefruit. This might explain the potentiating effect that grapefruit juice has on tramadol.