Flashcards in Antifungals Deck (48)
What are the 2 forms of pathogenic fungi?
Filamentous fungi and yeast
What characterises yeast?
Divide by budding
What characterises filamentous fungi?
Elongated cells divided by cell walls. Divide by spores
Appear in yeast and filamentous form depending on environmental conditions
5 antifungal targets
What is the main component of fungal cell walls?
beta 1-3 glucan
What is cholesterol equivalent component in the cell membrane of fungi?
What is the function of ergosterol?
Regulation of membrane permeability
Describe the formation of ergosterol
Squalene>squalene epoxidase>lanosterol>lanosterol 14 alpha demethylase>ergosterol
beta 1-3 glucan is a large polymer of what?
What enzyme synthesises beta 1-3 glucan?
beta 1-3 glucan synthase
What are the 4 classes of antifungals?
Give 2 examples of polyenes
Amphotericine B, Nystatin (not used anymore)
How do polyenes work?
Form pores in ergosterol membrane resulting in loss of membrane integrity and leakage of K+
Give 3 of fungi that AmB treats
Adverse effects of amphotericin B
Nephrotoxicity- pores form in human cell membranes
How is amphotericin B administered for serios/systermic infections?
How do lipid-associated Amphotericin B antifungals work?
Combining AmB to lipids minimises its delivery to kidney cells and reduces nephrotoxicity
In what cases is nystatin used?
Superficial infections e.g. oral/vaginal candidiasis
Clear cut nodule with cavity in teh middle of it. Fungus sits in the lung and causes localised infection.
Example of allyamines
What is terbinafine used for?
Athlete's foot-tinea pedis
How to allyalanines work?
Inhibit ergosterol synthesis
Is terbinafine broad spectrum or narrow spectrum?
Adverse effects of terbinafine?
Liver toxicity (jaundice, hepatitis)
Examples of dermatophyte infections that terbinafine is used to treat
Superficial fungal infections e.g. tinea pedis
Systemic use e.g. scalp ringworm, onychomosis
How do azoles work?
Inhibit ergosterol synthesis (lanosterol 14 alpha demethylase inhibitors)
Are azoles broad or narrow spectrum antifungals?
What antifungal is not effective against aspergillus?