Miscellaneous antifungal medications
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Miscellaneous antifungal medications
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Laboratory value | Result |
Complete blood count | |
Hemoglobin | 9 g/dL |
Leukocyte count | 4,100 /mm3 |
Platelet count | 90,000/mm3 |
Memory Anchors and Partner Content
External References
First Aid
2024
2023
2022
2021
Amphotericin B p. 194
Candida albicans p. , 150, 729
clinical use p. 195
Naegleria fowleri p. , 153
opportunistic fungal infections p. 150
systemic mycoses p. 149
Anemia
amphotericin B p. 195
Arrhythmias
amphotericin B p. 195
Blastomyces spp.
amphotericin B p. 195
Candida spp.
amphotericin B p. 195
Fever
amphotericin B p. 195
Hypotension
amphotericin B p. 195
Mucor spp.
amphotericin B for p. 195
Nephrotoxicity
amphotericin B p. 195
Phlebitis
IV amphotericin B p. 195
Potassium
amphotericin B p. 195
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Transcript
Content Reviewers
Antifungal agents are a class of medications used to treat mycoses, or fungal infections.
Mycoses can be superficial, meaning they are localized on the skin, or develop into systemic infections in immunodeficient patients.
Antifungals work either through fungistatic action, meaning that they inhibit fungal growth, or through fungicidal action, meaning they kill the fungi.
Now, antifungals include the azole family and a novel class of medications, echinocandins; but there are also many other antifungals with similar or different mechanisms that we’ll talk about in this video.
Okay, most fungal cells have a tough outer cell wall and an inner cell membrane.
The cell membrane is mostly made of phospholipids with some sterol or modified steroid molecules mixed in.
Humans have cholesterol, while fungi have ergosterol. Both sterol molecules help keep the cell membrane stable at a wide range of temperatures.
Now, the precursor to both molecules is lanosterol.
The precursor of lanosterol is squalene.
The conversion of squalene to lanosterol is catalyzed by an enzyme called squalene epoxidase.
Fungi have a cytochrome p450 enzyme called fourteen-alpha-demethylase in their mitochondria and endoplasmic reticulums, which converts lanosterol to ergosterol.
Without ergosterol, the structure of the cell membrane will be disrupted.
This will cause membrane-bound proteins, like ion channels, to stop working properly.
The membrane also becomes fragile, which eventually leads to inhibition of fungal growth.
Okay, let’s start with polyenes, which are naturally-derived antifungal antibiotics that alter cell membrane permeability.
They include amphotericin, also called amphotericin B, and nystatin.
Polyenes have both hydrophilic, meaning they love water, and lipophilic, meaning they love fats, characteristics.
They bind to ergosterol, and the hydrophilic core causes the formation of artificial pores in the cell membrane, thereby creating a leaky membrane.
This causes significant changes in ion balance including the loss of intracellular potassium.
Depending on their concentration, polyenes are either fungistatic or fungicidal.
Now, amphotericin B is one of the most important medications for the treatment of systemic mycoses. It’s used to fight systemic infections caused by Aspergillus, Blastomyces, Candida albicans, Cryptococcus, Histoplasma, and Mucor, either alone or in combination with other drugs.
Summary
There are a few different types of antifungal medications, but they all work in similar ways. Most of them work by disrupting the formation of the fungal cell wall, which eventually kills the fungus. Some common antifungal medications include azoles (such as fluconazole and itraconazole), polyenes (such as amphotericin B and nystatin), and echinocandins (such as caspofungin and anidulafungin).
Sources
- "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
- "Rang and Dale's Pharmacology" Elsevier (2019)
- "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)
- "The antifungal pipeline: a reality check" Nature Reviews Drug Discovery (2017)
- "Onychomycosis" Journal of the American Academy of Dermatology (2019)
- "New Antifungal Agents and New Formulations Against Dermatophytes" Mycopathologia (2016)