Pharm 4 Exam 2 & 3 Flashcards
Components of fungi cell walls
- Chitin
- Egesterol
- Beta Glucans
- Structural Proteins
Ergosterol Pathway
The CP450 enzyme 14a-sterol demethlase converts lanosterol into ergoesterol
Subcutaneous and systemic Mycoses
- Azoles
- Echinocandins
- Polyenes
- Prymadine Antifungals
MOA for Azoles
Inhibition of CELL MEMBRANE BY Inhibiting ergoesterol synthesis by direct inhibition of 14a demythlase.
Side effects of Azoles
- Mild GI
- Hepatotoxicity (rarely)
Contraindications of Azoles
None
MOA of Echinocandins
Inhibition of fungal CELL WALL synthesis, which weakens the wall. By inhibition of beta 1-3 glucan synthase.
Contraindications of Echinocandins
None
Side Effects of Echinocandins
- Mild GI N/V
- Infusion reactions
MOA of Polyenes
Polyenes bind to ergosterol creating pores within the CELL MEMBRANE, causing an escape of H+ and K+ leading to cell death.
Contraindications of Polyenes
Renal dysfunction
Side Effects of Polyenes
- Nephrotoxicity
- Infusion reactions
- Electrolyte imbalances
Define the depletion theory of the interaction between Azoles an Polyenes.
Preexposure to Azoles depletes the fungal cells of ergosterol, leading to fewer targets for polyene, resulting in antagonism
Define the enhancement theory of the interaction between Azoles an Polyenes.
Preexposure to Polyene leads to the formation of pores that facilitate greater access for azoles to the intercellular space leading to an additive effect
Pyrimidine Antifungals MOA
It is taken up by cytosine permeases which are specific to fungal cells. It is converted to 5FU then 5FdUMP which inhibits Thymine synthase leading to termination of DNA synthesis and cell division.
