Fungal IV Flashcards
What kind of centre do echinocandins have?
Cyclic
What is the mode of action of echinocandins?
Inhibition of glucan synthase - binds to Fks1p subunit and blocks beta1,3-D-glucan synthesis. This form of gluten gives the cell wall rigidity and so if it is lost the cell wall becomes weakened. Humans don’t have cell walls
What do all echinocandins have activity against?
Aspergillis and candida
What do echinocandins have no activity against?
Cryptococcus, mucoraceous moulds and dimorphic moulds
What are the three types of echinocandins?
Caspofungi, Anidulafungin, Micafungin
What is micafungins licence?
Entirely candidacies
Which drug can be used for empiric therapy?
Caspofungin
What form are all the echinocandins in?
IV as they are very large
Which is less toxic, caspofungin or amphotericin B?
Caspofungin
How are echinocandins metabolised?
Undergo spontaneous breakdown in tissues and are broken up by peptidases
Which drug can cause a loss of potassium?
Caspofungin
Which drugs can cause mild deranged liver functions?
Caspofungin and Micafungin
Why is C.albican resistant?
Mutations in gene for Fks1p gene of beta1,3-D gluten synthase complex
Particularly codon 645 Ser to Pro, Tyr, Phe
Why is C.glabrata resistant?
Mutations in Fks1p and 2 genes associated with echinocandin resistance
Why is cryptococcus not susceptible?
Gluten synthase is altered
When does up regulation in chitin concentration occur?
When candida species grown in presence of caspofungin at concentration below the MIC
What class is terbinafine drugs?
Allylamine class
What is the mode of action for terbinafine?
Inhibition of squalene epoxidase
What are the formulations of terbinafine?
Tablets, gel, cream and spray
How much terbinafine is bioavailable?
45% and heavily protein bound
Where are high concentrations of terbinafine is seen in?
Skin and nail
How is terbinafine eliminated?
80% urine and 20% faeces
What toxicity can terbinafine cause?
Liver deregulation and altered taste perception
