Anti Fungal And Viral Drugs Flashcards
How do polyenes work against fungi? What is a problem with this?
They bind to the ergosterol in the fungus cell wall and this causes an increase in cell wall permeability.
This also works on cholesterol in mammalian cell membranes so they are very toxic.
How is amphotericin B (polyene) administered and what are some effects of its toxicity?
It is given intravenously and is used to treat serious systemic fungal infections.
It has renal, hepatic and cardiac toxic effects.
How is nystatin (polyene) applied and what is it used to treat?
It is applied topically.
It can be a cream for fungal skin infections, in pessaries for vaginal Candida infections and as an oral suspension for oral and oesophageal candidiasis.
How do Azoles work against fungi?
They inhibit ergosterol synthesis.
How is fluconazole (azole) administered against yeast infections and what is an emerging problem with it?
Administered parenterally and orally. Some emerging resistance from some candida species.
How do allylamines work against fungi?
They inhibit the synthesis of ergosterol but to a different stage of the pathway than azoles.
What is the only allylamine in common use? What does it act against?
Terbinafine acts against dermatophyte infections of the skin such as ringworm and athletes foot.
How do echinocandins work? What are they used for? Name an example
They inhibit the synthesis of glucan polysaccharide in several types of fungi. They are only used for serious candida and aspergillus infections on specialist advice.
Micafungin
Caspofungin
Anidulafungin
How do anti viral drugs work?
They are virustatic and they interfere with nucleic acid synthesis.
How is aciclovir converted to its active form and what does it work against?
Thymidine kinase is coded for by the virus and converts the drug to its active form.
It is active against herpes simplex and varicella zoster virus.
The IV form is given against herpes encephalitis and VZV pneumonitis (serious infections)
Can also be given topically and orally.
How is HIV usually treated with drugs currently?
Usually used a combination of the three drugs zidovudine, nevirapine and saquinavir. These act on the stages of HIV replication. These analogue reverse transcriptase inhibitors and either a non nucleoside reverse transcriptase inhibitor or a viral protease inhibitor.
What is a common treatment of drugs for chronic Hepatitis B or C?
Interferon-a and oral Ribavirin is a common treatment for Hepatitis C.
Adefovir dipivoxil used for Hepatitis B.
What drugs are useful for viral respiratory infections?
Ribavirin is useful for Respiratory syncytial Virus infections as an inhaled spray.
Zanamivir and oseltamivir are used to treat influenza A or B within 48 hours of onset of symptoms.
