**Antifungal Drugs: Chapter 15**

I. Overview

Fungi are organisms capable of causing diseases in humans, animals, and plants. Fungal infections can occur in various organs and body systems, from skin and mucous membranes to internal organs. Antifungal drugs are used to treat fungal infections.

II. Classification of Antifungal Drugs

Antifungal drugs are classified based on their mechanism of action and spectrum of activity:

1. By Mechanism of Action:

• Polyene group: Binds to sterols in the fungal cell membrane, increasing permeability and causing fungal cell death.

• Examples: Nystatin, Amphotericin B, Natamycin, Candicidin.

• Azole group: Inhibits the enzyme 1,4-α-demethylase, preventing the synthesis of ergosterol, a crucial component of the fungal cell membrane.

• Examples: Ketoconazole, Miconazole, Itraconazole, Fluconazole.

• Allylamines group: Inhibits the synthesis of squalene epoxidase, an enzyme essential for ergosterol synthesis.

• Examples: Terbinafine, Naftifine.

• Pyrimidine group: Binds to fungal RNA, inhibiting protein and DNA synthesis.

• Examples: Flucytosine.

• Griseofulvin group: Binds to microtubules in fungi, inhibiting nucleic acid synthesis and fungal polymerization.

• Examples: Griseofulvin.

2. By Spectrum of Activity:

• Narrow-spectrum antifungal drugs: Only effective against certain types of fungi.

• Examples: Nystatin, Clotrimazole.

• Broad-spectrum antifungal drugs: Effective against various types of fungi.

• Examples: Amphotericin B, Fluconazole, Itraconazole.

III. Common Antifungal Drugs

1. Polyene group:

• Nystatin: A narrow-spectrum antifungal drug, effective against yeasts, mainly Candida.

• Uses: Treats topical Candida infections like oral thrush and vaginal yeast infections.

• Note: Only for topical use, not for systemic administration.

• Amphotericin B: A broad-spectrum antifungal drug, effective against various fungi, including yeasts and molds.

• Uses: Treats severe systemic fungal infections, including fungal bloodstream infections and fungal meningitis.

• Note: Has significant side effects, requiring close monitoring during use.

2. Azole group:

• Ketoconazole: A broad-spectrum antifungal drug, well absorbed through the gastrointestinal tract.

• Uses: Treats skin and mucous membrane infections, nail fungus, hair fungus, and internal fungal infections.

• Note: Can cause side effects such as digestive disturbances, liver dysfunction, and hormonal imbalances.

• Miconazole: A broad-spectrum antifungal drug, used topically or vaginally.

• Uses: Treats skin and mucous membrane infections, nail fungus, and hair fungus.

• Note: Only for topical use, not for systemic administration.

• Itraconazole: A broad-spectrum antifungal drug, well absorbed through the gastrointestinal tract, with the ability to distribute to various tissues and organs, especially nails and hair.

• Uses: Treats internal fungal infections, nail fungus, hair fungus, skin and mucous membrane infections.

• Note: Can cause side effects such as digestive disturbances, liver dysfunction, and hormonal imbalances.

• Fluconazole: A broad-spectrum antifungal drug, well absorbed through the gastrointestinal tract, with the ability to distribute into cerebrospinal fluid.

• Uses: Treats Candida infections in AIDS patients, Cryptococcus infections in the central nervous system, Candida urinary tract infections, and Candida vaginal infections.

• Note: Can cause side effects such as headache, nausea, and diarrhea.

3. Allylamines group:

• Terbinafine: A broad-spectrum antifungal drug, well absorbed through the gastrointestinal tract, with the ability to distribute into nails and hair.

• Uses: Treats nail fungus, hair fungus, and skin infections.

• Note: Can cause side effects such as digestive disturbances, headache, and itching.

• Naftifine: A broad-spectrum antifungal drug, used topically.

• Uses: Treats skin infections, nail fungus, and hair fungus.

• Note: Only for topical use, not for systemic administration.

4. Pyrimidine group:

• Flucytosine: A narrow-spectrum antifungal drug, effective against yeasts, mainly Candida.

• Uses: Treats severe Candida infections, Candida meningitis, and Candida bloodstream infections.

• Note: Can cause side effects such as digestive disturbances, bone marrow suppression, and liver dysfunction.

5. Griseofulvin group:

• Griseofulvin: A narrow-spectrum antifungal drug, effective against molds, mainly dermatophytes.

• Uses: Treats nail fungus, hair fungus, and skin infections.

• Note: Requires long-term use and can cause side effects such as nausea, diarrhea, headache, and dizziness.

IV. Precautions When Using Antifungal Drugs

• Consult a Doctor: Before using any antifungal medication, consult with a doctor for accurate diagnosis and appropriate treatment.

• Adhere to Dosage and Duration of Treatment: Use the medication at the correct dosage and for the duration prescribed by the doctor for optimal treatment effectiveness and minimization of side effects.

• Monitor Side Effects: While using antifungal medications, carefully monitor for potential side effects. If you encounter any issues, immediately report them to your doctor.

• Drug Interactions: Antifungal medications can interact with other drugs, so inform your doctor about all the medications you are taking to avoid adverse interactions.

• Caution in Pregnant and Breastfeeding Women: Antifungal medications can be harmful to the fetus and infants, so caution is required when used by pregnant and breastfeeding women.

• Proper Storage: Store antifungal medications in a dry, cool place, away from direct sunlight.

V. Conclusion

Antifungal drugs are a crucial group of medications in treating fungal infections. Understanding the mechanism of action, spectrum of activity, and precautions when using antifungal medications is essential to ensure treatment effectiveness and minimize side effects.

Note: This article is for informational purposes only and should not be considered a substitute for professional medical advice.