Slide 28 of 76
Notes:
- A P450 enzyme inhibitor is any drug that inhibits the metabolism of a P450 substrate
- This inhibition process is generally competitive in nature (I.e., the inhibitor competes with a substrate for binding at the enzyme’s binding site), and is reversible.
- This competitive mechanism results in accumulation of the target drug (substrate). However, once the inhibitor is gone, metabolism is back to normal.
- NB: a drug does not necessarily need to be a P450 substrate to be an enzyme inhibitor (e.g., fluconazole is primarily renally excreted, but is a moderate to weak P450 inhibitor)
- Enzyme inhibitors vary in both selectivity and potency, in terms of their effects on CYP enzymes.
