Antivirals and anti fungals Flashcards
(29 cards)
describe a basic virus lifecycle
attaches penetrates uncoats and release genome genome transcripes/translated virus is 'synthesised' and released
RECAP: FHV-1 is responisble for what disease in felines?
infectious upper resp tract diseases
more severe than calcivirus
RECAP: What is the pathogenesis of FIP?
ingested and replicates in tonsils –> spreads and leads to viraemia. 2 types dry and wet
what antivirals have been used in successful treatment of FIP?
none cure. can delay death.
What are the 2 main types of fungi
fungal hyphae and yeasts
give an example of a superficial and systemic fungal infection
superficial - dermatophytosis
systemic - cryptococcosis
what type of fungus is Malassezia pachydermatitis and desc features
yeast overgrowth.
commensal
ears and skin –> inflam and itching
usually secondary
How are fungi so difficult to affect with anti-fungals
cell wall and membrane capsules in addition sometimes many anti-f are f-statics fungi = eukaryotes making it difficult not to effect mammalian cells! must treat long after clinical cure!
Decsr the fungal cell wall
xlinked glycop, glucan and chitin
synthase enzymes make it all^^
main pharm target as not on animal cells!
if mammal cells have a cell wall how can fungi cell wall be targeted pharm’ically?
25% composed of egosterol (equiv to cholesterol)
What synthesises ergosterol?
lanosterol 14 alpha-demethylase
What are cytochrome p450 enzymes?
membrane assoc proteins in most tissues. fct as drug metab in the liver
why are the cyto p450 enzyme-drug interactions important?
some will either inhibit C-p450 or increase its activity. this either results in less effective doses or toxicity!
What is tha main target of Azoles
Ergosterol by inhib cyto p450 and (lanosterol 14 alpha-demethylase)
what are the 2 groups of Azoles?
triazoles - (itraconazole)
Imidazoles - (miconazole)
Descr the basic PK info of Azoles
broad spect
rapid abs inc with food
widely distubuted and p-bound
Liv;liv
What is the benefit with Triazoles
higher affinity and specifity for:
- fungal cytoc p450
- fungal cell wall
- cidal at lower levels
- residual conc in hairs and skin
Desc some of the side effect from Azoles
vasculitis teratogen GI upset hepatotox cats = sensitive
Name a systemic azole
Fluconazole. cyrptococcus inf and urinary inf as excreted by kidneys mainly
What do allylamines target?
enzyme which synthesises the enzyme which makes ergosterol! (squalene epoxidase)
Name an Allylamine
Terbinafine
what might terbinafine (allylamine) be able to treat
not licensed
tx - dermatophytosis and malassezia (yeasts+)
do the allylamines effect cytochrom p450?
NO
What are the topical polyene antibiotics (stop egorsterol binding)
Nystatin. topical for ear drops (otitis ext) - CANURAL
and malassezia
