LEC 2 - Antifungals Flashcards
What are the three categories of a fungal disease?
Superficial
Subcutaneous
Systemic
What is involved in a systemic fungal infection?
Normally start in the lungs
Then spreads to other organs
What is involved in a subcutaneous fungal infection?
Dermis
Subcutaneous tissues
Occasionally adjacent
What is involved in a superficial fungal infection?
Skin
Other keratinized structures
Mucous membranes
Are most antifungals -cidal or -static?
Fungistatic
What is clearance of a fungus in a host most dependent?
Host’s response to the presence of the fungus
When is clearance in a host unlikely in regards to a fungus?
Immunosuppressed animals
Primary/Secondary immunodeficiency disease
What are the three major reasons that treating a fungal infection takes so much longer than a bacterial infection?
Grow more slowly
Most medications are -static so immune system has to work
Fungus can cause inflammatory response making worse
What are the four major classes of antifungals?
Allylamines
Azoles
Echinocandins
Polyenes
Spectrum: Allyamines
Broad
Major drugs: Allyamines
Naftitine
– and –
Terbinafine
Administration route: Naftitine
Topical
Administration route: Terbinafine
Topical + Systemic table
Action: Allyamines
Inhibit activity of squalene epoxidase
What happens when the activity of squalene epoxidase is inhibited?
Lack of ergoseterol + Increased squalene
= Toxic effect
Where does terbinafine concentrate in the body?
Dermis
Epidermis
Adipose tissue
Nails
What can terbinafine be used for?
Dermatophytes
Aspergillus spp.
Dimorphic fungi
Yeast
Spectrum: Azoles
Fungistatic + Broad
Activity: Azoles
Inhibition of sterol 14-a demethylase
Groups: Azoles (not specific medications)
Imidazoles
— and –
Triazoles
What does the inhibition of sterol 14-a demethylase cause?
Depletion of ergosterol and increase in 14-a methylsterols
Disrupts fungal membrane + growth
What is important to remember when giving an azole to an animal?
Cytochrome P450 dependent - can cause serious drug interactions
What animal is the use of Azoles contraindicated in? Why?
Pregnant animals
due to Teratogenicity
Medications: Imidazoles
Ketoconazole
Clotrimazole
Miconazole
Econazole
Medications: Triazoles
Fluconazole
Itraconazole
Voriconazole
Posaconazole
Which, Imadazoles or Triazoles, has greater affinity for fungus?
Triazoles