last updated 24-06-2024



The imidazoles and triazoles inhibit fungal ergosterol synthesis by inhibiting the P450 dependent 14α-demethylase. Since ergosterol is an essential compound of the membrane, its absence causes holes in the membrane. As a consequence the fungal cell content (ions, small molecules like amino acids etc.) leaks from the fungal cell.

Triazoles (voriconazole and fluconazole) are more slowly metabolised and have less adverse effects on human sterol synthesis than do the imidazoles (ketoconazole).

Because of their inhibition of a P450 enzyme system, the azoles have interactions with many drugs that depend on metabolism in the liver. Drug interactions are responsible for many of the side effects, however, azoles themselves cause gastrointestinal distress.


Azoles interfere with cytochrome P450 enzymes in the sterol synthesis pathway. 


Triazoles are newer drugs and have a wider range of antifungal activity than imidazoles.