fungistatic

Fungistatic refers to a substance or agent that inhibits the growth and replication of fungi rather than directly killing them. In many infections, the immune system must clear the pathogens once their growth is slowed. The designation fungistatic is relative to the organism and the drug concentration; some agents may be fungistatic against certain fungi and fungicidal against others.

Most clinically used fungistatics act by disrupting essential fungal processes, such as ergosterol synthesis, nucleic acid synthesis, or microtubule function. Inhibitors of ergosterol synthesis include azoles (for example fluconazole, itraconazole, voriconazole) and allylamines (such as terbinafine). These drugs interfere with membrane integrity, impairing fungal growth. Nucleic acid synthesis inhibitors, like flucytosine, disrupt DNA and RNA production, while griseofulvin interferes with microtubule formation and fungal mitosis. The result is slowed growth rather than immediate fungal death.

Clinically, fungistatic therapy relies on an intact host immune response to eradicate infection. Pharmacodynamic considerations often emphasize exposure over peak concentration and may involve longer treatment courses. These agents can have favorable toxicity profiles compared with fungicidal drugs but may still cause adverse effects and drug interactions, particularly azoles that inhibit cytochrome P450 enzymes.

Examples of fungistatic drugs include fluconazole, itraconazole, and voriconazole; terbinafine has variable fungistatic versus fungicidal activity depending on the organism; griseofulvin is primarily fungistatic for dermatophyte infections; and flucytosine can be fungistatic or fungicidal depending on organism and dose.

In summary, fungistatic describes a growth-inhibiting mechanism used by many antifungal therapies, with efficacy closely tied to the host’s immune response and the specific pathogen.