Anti viral and Anti fungal drugs Flashcards
Relatonship between antibiotics and fungi and antibiotics and virus
The majority of antibiotics have no action on fungi and fungal infection and no action against virus
How can fungi be subdivided?
-yeasts and filamentous fungi (moulds)
What are the classes of anti fungal drugs?
- Polyenes
- Azoles
- Allylamines
- Echinocandins
What are polyenes?
- Anti fungal drugs
- Bind to ergosterol and is present in the fungal cell wall but not in the bacterial cell wall
- this results in an increase in the permeability of the cell wall
What are polyenes active against?
- Both yeasts and filamentous fungi
- Unfortunately polyenes also bind to other sterols (e.g. cholesterol) in mammalian cell membranes and this is the reason for their toxicity
Examples of polyene drugs
-Amphotericin B
and Nystatin
How does amphotericin B (polyene) work?
- only drug available for intravenous use and is used for the treatment of serious systemic fungal infection
- extremely toxic with a wide range of side effects including renal, hepatic and cardiac toxicity
How does Nystatin (polyene) work?
- Available for topical use only
- eg creams for fungal skin infections
What are Azoles and how do they work?
- antifungal drug
- inhibition of ergosterol synthesis
Examples of Azoles
Fluconzaole, itraconazole,
voriconazole
What can fluconazole treat?
Anti fungal drug
- oral and parenteral treatment of yeast infections
- no serious toxicity problems
What can itraconazole drugs treat?
- active against both Yeats and filamentous fungi
- aspergillum spp. and dermatophytes
What can voriconzole treat?
To treat aspergillosis
What are Allylamines?
-anti fungal drugs which suppress ergosterol synthesis but act at a different stage of the synthetic pathway from azoles
What are Allylamines active against?
- Dermatophyte infections of the skin
- e.g. ringworm, athletes foot, nails
What are Echinocandins?
anti fungal drug which inhibit the synthesis of glucan polysaccharide in several types of fungi
When are Echinocandins used
For serious Candida and Aspergillus infections
Examples of Echinocandins?
Caspofungin, Micafungin, Anidulafungin
What stage is anti viral therapy at?
An early stage of development and there are few agents available
What is an issue with viruses?
Few viral diseases are treatable
What can kill viruses?
Nothing. There are no virucidal agents (those that will kill the virus)
What does anti viral therapy involve?
- They are all Virustatic agents i.e. inhibit growth and/or replication
- anti-viral drugs are nucleoside analogues which interfere with nucleic acid synthesis
What are examples of anti virus drugs?
- anti-herpes virus drugs
- anti HIV drugs
- drugs for chronic hepatitis B and C
- drugs for viral respiratory infections
What are examples of anti-herpes virus drugs?
- Aciclovir
- Valaciclovir and Famciclovir
- Valganciclovir
- Gangiclovir
When is aciclovir used?
Extremely active against Herpes Simplex virus and active against Varicella Zoster virus
When is famciclovir used?
Treatment of HSV and shingles
Examples of anti-HIV drugs?
- Zidovudine
- combination therapy with at least three drugs Is now normal practise
- Two nucleoside analogue reverse transcriptase inhibitors plus either a non-nucleotide reverse transcriptase inhibitor (nevirapine) or a viral protease inhibitor (saquinavir)
Examples of drugs for chronic hep B and C?
-Interferon-a, advantage is its given orally
examples of drugs for viral respiratory infections?
- Zanamivir
- Oseltamivir
- ribavirin
