Polyene Antifungals Mechanism Quiz

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Questions and Answers

What is specifically inhibited by Echinocandin and Pneumocandin in fungi?

Chitin synthesis

Beta-glucan synthase (correct)

Nucleic acid replication

Ergosterol biosynthesis

What is the target of Echinocandin and Pneumocandin in fungal cells?

Mitochondrial ATP production

Cytoplasmic ribosomes

Nuclear membrane

Cell wall synthesis (correct)

Which enzyme's inhibition is targeted by Squalene Epoxidase Inhibitors?

Squalene isomerase

Δ14- reductase

Squalene epoxidase (correct)

14α- demethylase

What is the primary effect of Allylamines and Related Compounds on fungi?

Increase squalene levels Signup and view all the answers

What is the impact of Squalene Epoxidase Inhibitors on fungal ergosterol levels?

Decrease Signup and view all the answers

What is the narrow spectrum of activity of Allylamines and Related Compounds primarily limited to?

Nail and skin dermatophytes Signup and view all the answers

How do polyenes like Amphotericin B and Nystatin act on fungal cells?

Binding to ergosterol in the cell membrane and forming pores Signup and view all the answers

Which polyene antifungal has been reported to cause nephrotoxicity?

Amphotericin B Signup and view all the answers

What toxic effect does Amphotericin B have on host immune cells?

Causing inflammation and release of cytokines Signup and view all the answers

What leads to cell death in fungal cells upon binding of polyene antifungals like Amphotericin B?

Formation of pores increasing membrane permeability Signup and view all the answers

How does Amphotericin B interact with cell membranes to form transmembrane channels?

By binding with ergosterol Signup and view all the answers

Which statement is true about the binding preference of polyenes to cell membranes?

They bind preferentially to cholesterol-containing membranes Signup and view all the answers

Why are amphotericin B and Nystatin considered polyenes?

Due to their mechanism of action on fungal cell membranes Signup and view all the answers

What is a key toxic effect associated with the use of polyenes like amphotericin B and Nystatin?

Nephrotoxicity Signup and view all the answers

How do polyenes like Nystatin and amphotericin B exert their antifungal effects?

By disrupting fungal cell membrane integrity Signup and view all the answers

Which of the following describes the mechanism of action of polyenes like Nystatin and amphotericin B?

Targeting ergosterol in fungal cell membranes Signup and view all the answers

What is a common characteristic of the toxicities seen with polyenes such as Nystatin and amphotericin B?

Increase in creatinine levels (nephrotoxicity) Signup and view all the answers

Why is it essential to monitor renal function in patients being treated with polyenes like Nystatin and amphotericin B?

To detect and manage nephrotoxicity Signup and view all the answers

Study Notes

Echinocandin and Pneumocandin

Echinocandin and Pneumocandin specifically inhibit the synthesis of beta-1,3-glucan in fungal cell walls.
Their main target in fungal cells is the enzyme 1,3-beta-D-glucan synthase, crucial for cell wall integrity.

Squalene Epoxidase Inhibitors

Squalene Epoxidase Inhibitors target the enzyme squalene epoxidase, which is involved in ergosterol biosynthesis in fungi.
These inhibitors result in reduced levels of ergosterol, causing disruption in fungal cell membrane integrity.

Allylamines and related compounds primarily affect fungi by inhibiting the enzyme squalene epoxidase, which is essential for sterol synthesis.
Their spectrum of activity is predominantly narrow, primarily targeting dermatophytes and certain yeasts.

Polyenes Antifungal Activity

Polyenes, such as Amphotericin B and Nystatin, act on fungal cells by binding to ergosterol in the cell membrane, leading to the formation of pores.
This pore formation causes increased cell permeability and ultimately results in cell death due to leakage of essential cellular components.

Nephrotoxicity and Immune Effects

Amphotericin B is known to cause nephrotoxicity, which can lead to renal impairment in patients.
It also has a toxic effect on host immune cells, potentially leading to an inflammatory response that further complicates treatment.

Mechanism of Action for Polyenes

Upon binding to cell membranes, polyenes like Amphotericin B form transmembrane channels that disrupt homeostasis.
Polyenes exhibit a higher binding preference for fungal membranes compared to mammalian membranes, which mitigates some toxicity.

Toxicity and Monitoring

Key toxic effects associated with polyenes include renal toxicity and electrolyte imbalances.
It is crucial to monitor renal function in patients on polyene therapy due to the risk of nephrotoxicity associated with these antifungals.

Common Characteristics of Polyene Toxicities

Toxicities observed with polyenes such as Nystatin and Amphotericin B often include nausea, fever, chills, and renal impairment across patients.

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Description

Test your knowledge on the mechanism of action of polyene antifungal drugs such as Natamycin, Amphotericin B, and Nystatin. Learn how these drugs bind to ergosterol in fungal cell membranes, leading to pore formation and cell death. Prepared based on Dr. Ghaith Mansour's lecture at Al-Balqa Applied University.