Antimicrobial chemotherapy-antivirus and antifungal drugs Flashcards
What are characteristics of polyenes? (antifungal)`
Polyene drugs bind to ergosterol, present in the fungal cell wall but not in the bacterial cell wall, and this results in an increase in the permeability of the cell wall.
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.
What are characteristics of Amphotericin B (polyene)?
The 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.
Resistance to amphotericin B is unusual
What are characteristics of Nystatin? (polyene)
available for topical use only
(e.g. in creams for fungal skin infections, in pessaries for vaginal candida infections,
oral suspension for oral and oesophageal candidiasis)
Describe the azoles (anti fungal drug)?
the azoles are going to inhibit the ergosterol synthesis and prevent proper formation of the cell wall
What are characteristics of fluconazole (azole)?
treatment of yeast infection
no serious toxicity problems
resistance among some candida species
What are characteristics of Itraconazole (azole)?
for treating yeast and filamentous fungi
What is Voriconazole (azole) used to treat?
aspergillosis
Describe Allylamines (antifungal drugs)?
suppress ergosterol synthesis but act at a different stage of the synthetic pathway from azoles
What is the only allyamine in common use?
terbinafine
What are allyamines used to treat?
Active against dermatophyte infections of the skin (e.g., ringworm, athlete’s foot) and nails (onychomycosis).
Mild infections are treated topically and more serious infections (including onychomycosis) orally.
Describe Echinocandins? (antifungal)
Inhibit the synthesis of glucan polysaccharide in several types of fungi
What are echinocandins used to treat?
These agents are used for serious Candida and
Aspergillus infections, usually on specialist advice
What do you prescribe for a flu?
If there is a flu, no prescription of antibiotics, instead opt for anti-viral
What is the availibility to treat viruses like?
There are no virucidal agents (i.e. those that will kill the virus)
but that they are all virustatic (i.e. inhibit growth and/or replication)
Describe the common structure of antiviral drugs?
Many anti-viral drugs are nucleoside analogues which
interfere with nucleic acid synthesis.
What are characteristics of the anti-herpes virus drugs (anti viral drugs)?
Herpes viruses are a clinically important group.
They are not all equally sensitive to anti-viral agents.
Treatment is most effective if started early but does not eradicate any of these viruses-treats infection.
Give characteristics of Aciclovir? (Anti-herpes virus drugs)
Nucleoside analogue.
It is specific for virus-infected cells and has very low toxicity for uninfected host cells.
Extremely active against Herpes Simplex virus and is active against Varicella Zoster virus.
What are Valaciclovir and Famciclovir used to treat (Anti-herpes drugs)?
Treatment of HSV and shingles
What is Valganciclovir?
pro drug, becomes itself when metabolized in body
good choice for CMV
presents bone marrow toxicity
What is Ganciclovir?
coming from metabolism of valganciclovir
active against CMV
toxic
restricted to treating patients that are in the presence of or having life threatening infections or if they are immunocompromised
What is Foscarnet?
can be used for HSV, VZV and CMW (resistant to nucleoside analogues)
What is Cidofovir?
Cidofovir is used for CMV retinitis when other anti-viral drugs are inappropriate.
What is zidovudine (Anti-HIV drugs)?
Is a nucleoside analogue interfering with the action of reverse transcriptase.
(It slows the replication of the virus but does not kill it).
Had side effects of anaemia and neutropenia
What do we nowadays use to treat HIV?
Combination therapy with at least three drugs
is now normal practice in HIV treatment.
Drugs are active on at least two different stages of HIV replication.
Two nucleoside analogue reverse transcriptase inhibitors,
plus either a non-nucleoside reverse transcriptase inhibitor (nevirapine)
or a viral protease inhibitor (saquinavir).
What is used to asses response to treatment?
patients viral load and CD4+ cell count
What is interferon-alpha? (drugs for chronic hepatitis b and c)
Protein that, forms part of the host immune response.
Produced by genetic engineering and is used to treat selected chronic hepatitis B and C infections
-has to be given intraveneously
What is ribavirin?
can be used in combination with interferon alpha for successful treatment of chronic hepatitus C
What is adefovir dipivoxil and lamivudine?
Lamivudine used mainly for HIV treatment, with adefovir dipivoxil also suitable
for selected patients with hepatitis B.
What are Zanamivir and Oseltamivir used for?
drugs for viral respiratory infections
Treatment of influenza A or B within 48 hours of the onset of symptoms and for post-exposure prophylaxis.
What is ribavirin used for?
drug for viral respiratory infections
Occasionally used for treatment of severe Respiratory Syncytial Virus (RSV) infections. It must be inhaled as a fine spray to reach the site of infection
in the lungs, administration is difficult.
What is remdesivir?
drug for viral respiratory infection
Is an adenosine nucleoside triphosphate analogue, interfering with the action of viral RNA-dependent RNA polymerase.
It is classified as a direct-acting antiviral agent SARS-CoV-2 (COVID-19) infections.
What method is used for choosing rational treatment in selected patients?
genotypic analysis
