Azole

Group of antifungals that inhibit the ergosterol synthesis of fungal cells. This leads to a fungistatic effect. The characteristic feature of azoles is the five-membered heterocyclic ring, which is complexly substituted. Depending on the number of nitrogen atoms in the ring, a distinction is made between the

• imidazoles ( 2 N atoms) - (e.g. Canesten®)
• from the
• triazoles (3N atoms) - (e.g. Sempera®)

The microsomal enzyme lanosterol demethylase, a cytochrome P450 isoenzyme of fungi, which catalyses the synthesis of ergosterol from other steroid precursors, is specifically inhibited. Inhibition of the cytochrome P450 isoenzyme leads to a deficiency of this essential building block of the cytoplasmic membrane and thus to massive disruption of membrane function, which gradually disrupts growth and increases vulnerability to external influences (fungistatic effect). The subsequent accumulation of toxic precursors of ergosterol in the fungal cell causes irreversible damage to the cell, which dies after some time. With low potency the azole antifungal ketoconazole also inhibits human cyp-enzymes. Furthermore also the synthesis of testosterone.

1. Farm W: General mycology. In: Dual series, Medical Microbiology. 7th edition. Thieme publishing house Stuttgart S 483