Azole antifungals inhibit cytochrome P450 enzymes. What is a common clinical implication of this interaction?

• A. Induction of cytochrome P450 enzymes causing faster drug clearance.
• B. Inhibition of cytochrome P450 enzymes, increasing levels of coadministered drugs.
• C. Directly damaging fungal cell walls by forming pores.
• D. Inhibit DNA replication by cross-linking DNA.

Answer: (B)

CYP inhibition by azole antifungals means drugs that are normally broken down by these enzymes stay in the body longer. This leads to higher blood levels of coadministered medications and increases the risk of toxicity or exaggerated effects. For example, fluconazole can raise the levels of warfarin, some statins, benzodiazepines, and calcium channel blockers, among others, because their metabolism is slowed.

This differs from induction of CYP enzymes, which would speed up clearance and reduce drug levels. The other options describe antifungal actions that aren’t related to CYP metabolism—forming pores in fungal membranes or directly inhibiting DNA replication.