are metabolized into certain substances, active or inactive & more or less potent via the CYP3A4 & CYP2D6 liver enzymes.
So depending on what the opiate
in question is metabolized into, one should use either GFJ or Cimetidine accordingly for purposes of potentiation. SWIM
doesn't know of any opiates that are potentiated by CYP2D6 inhibitors (cimetidine, etc..).
More specifically tho:
is metabolized via CYP2D6 & into hydromorphone
(more potent) & norhydrocodone (via CYP3A4). Norhydrocodone is psychoactively inactive thus by inhibiting the CYP3A4 enzyme, hydrocodone is metabolized into hydromorphone to a greater extent by the CYP2D6 liver enzyme because the CYP3A4 enzyme is busy metabolizing the inhibitor (Grapefruit juice, etc..)
so if you know what the opiate in question is metabolized into & via what liver enzyme, you'll know which inhibitor will work most synergesically with said drug
Hope that sums it up more clearly