Antifungal Drugs

Antifungal drugs: Followings are major antifungal drugs:
1. Iodides: It is most commonly used for the treatment of sporotrichosis (cutaneous lymphatic form). Disseminated sporotrichosis is frequently resistant to iodide therapy. It is customary to begin treatment with potassium iodide with a dose of 1 ml of saturated solution three times a day which may be gradually increased to 12 to 15 ml per day. Treatment should be continued for at least 6 weeks.
2. Hydroxystilbamidine isethionate: It is an aromatic diamidine. Only B. dermatitides is susceptible. Contents of vial containing 225 mg should be added to 200 ml of glucose or saline solution & should be administer intravenously in 45 to 70 minutes.
3. Amphotericin B: It is an antibiotic derived from streptomyces nodosus. When suspended in liquid it is unstable at 37°C. Its mode of action is by binding to sterol present in the cell membrane of some fungi. Such binding increases permeability of The cell with leak of essential component like glucose & potassium. Susceptible fungi to amphotericin B are Blastomyces dermititidis, Histoplasma cap sulatum, Cryptococcus neoformans, candida, Sporthrix schenkil etc. Aspergillus are most frequently resistant. To the 50 mg vial, 10 ml of sterile water is added & vial is shaken for 3 minutes. This suspension is added to 5% glucose solution in a final concentration no greater than 10 mg per 100 ml. The contents are given intravenously over a 2 to 6 hour period
4. Griseofulvin: It is active against dermatophytes only. It causes stunting & shrinking of hyphae. Drug is administered orally 10 mg/Kg daily. Although symptomatic improvement is noticed after 2 to 3 days of administration, treatment must continue for at least 4 weeks.
5. Flucytosine: It is a fluorinated pyrimidine. Fungi like Crypto-coccus neoformans, candida, cladosporium are susceptible to it. It is administered orally 150 mg/Kg per day in equally divided 4 doses at 6 hour intervals.
6. Inzidazoles: In vitro it is effective in yeasts & filamentous fungi including dermatophytes. Little is known about its mode of action. However its relatively high concentration preferentially damage the fungal cell wall & plasma membrane making them permeable to intracellular amino acids, phosphates and potassium, thus, inhibiting intracellular macromolecular synthesis. Doses recommended are 100 mg/ Kg per day in children whereas in adults 1.5 gins every 6 hourly through oral route.
Other antifungal drugs are saramycetin (effective against histoplasmosis & dermatophytosis), hamycin (B. dermatitidis), tolnaftate (dermatophytes), nystatin (candida infection of skin & mucus membrane), pimaricin (keratitis due to fusarium) etc.

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