Anti fungal Drugs - The Veterinary Site

Anti fungal Drugs


Anti-Fungal Drugs

(by MAAZ AHMED SIDDIQUI)


Inflammatory condition caused by a fungus is called as mycosis. There are two types of mycosis:
1)      Systemic mycosis
2)      Subcutaneous/topical mycosis
Mycosis is mostly chronic in nature. Acute cases are not common or very rare. Systemic chronic mycosis is life threatening. Most of fungal infections cause immunosuppression in the body.
Oral administration of anti-fungal drugs is highly unsafe and causes adverse reactions in the body.
1.    Amphotericin B
Amphotericin B is normally added in culture medium to stop the fungal growth. This is naturally occurring polyene macrolides anti-mycotic which is obtained from Streptomyces nodosus. This is the drug of choice in systemic life threatening fungal infection. This is used in synergistic combination with another anti-fungal drug “Flucytosine”.
Mode of Action
It binds lipophilically or hydrophobically with the cell membrane of fungus and get access to ergosterol and forms channels in membrane which cause loss of K+ ions and other small molecules leading towards death of fungal cell.
Drug + Ergosterol => Porous Membrane having channels => Loss of electrolytes => Death
Amphotericin B has fungicidal (at high concentration) as well as fungistatic (at low concentration) action. Its action depends upon the concentration as well as kind of fungus that either it is less sensitive to fungus or more sensitive. It is effective against different genera of fungus:
Ä      Candida
Ä      Histoplasma
Ä      Cryptococcus
Ä      Coccidioides
Ä      Blastomyces

Resistance
Fungus decreases its ergosterol content in its cell membrane.
Amphotericin B administered alone will cause nephrotoxicity which will lead to kidney leakage of Na+ ions. So don’t use it in renal compromised patients. Salt of Amphotericin B “sodium deoxycholate” should administer with Amphotericin B through I/V route.
We can also coat Amphotericin B with phospholipids and cholesterol to decrease its damage to kidneys. Coated Amphotericin B is called as Liposomal Amphotericin B.
Amphotericin B (alone)
Amphotericin B (with its salt)
Amphotericin B (coated)
Huge damage to kidney
High damage to kidney
Less damage to kidney

Administer I/V slowly
Administer I/V slowly

Adverse Effects
Amphotericin B has low therapeutic index value or in other words has narrow therapeutic window. Its adverse effects are:
´        Induces chills and temperature
´        Renal impairment which will cause hypotension due to loss of ions
´        Normochromic normocytic anaemia
´        Severe damage to nervous system
´        Thrombophlebitis
´        Marked impotence in males
´        Hypokalemia


Anti fungal Drugs Anti fungal Drugs Reviewed by Maaz ahmed siddiqui on 08 May Rating: 5

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