Antivirals/Antifungals Flashcards
Name a M2 ion channel inhibitor and explain how they work.
- amantadine
- prevents uncoating of virus (an early step in replication)
- virustatic
Are M2 ion channel blockers prone to resistance?
Yes, resistance develops in 30% in a few days (due to resistance in M2 gene)
What is the spectrum of amantadine?
prevents and treats influenza A
Describe M2 ion channel inhibitor pharmacokinetics
- completely absorbed
- eliminated unchanged in urine
what are the side effects of M2 ion channel blockers
- amphetamine like effects
- mild GI upset
Name 2 neuraminidase inhibitor and how the work.
- zanamivir
- oseltamivir
- inhibits viral neuraminidase –> impairs release and spread of influenza virions by causing them to stick together
What is the spectrum of neuraminidase inhibitor?
prevents and treats influenza A and B infections
Describe the neuraminidase inhibitor pharmacokinetics.
- zanamivir (powder) is only 3% absorbed, then eliminated unchanged via urine. 1D dose causes active drug in the lungs for 24 hours
- oseltamivir ~80% absorbed, eliminated unchanged in urine. Elimination t1/2 = 3 hours
What are the side effects of zanamivir and oseltamivir?
Z - rare bronchospasm
O - nausea and vomiting
Give an example of a DNA polymerase inhibitor and explain how they work.
- acyclovir
- acyclovir becomes acyclovir-triphosphate and takes the place of guanosine in the DNA. This competitively inhibits viral DNA polymerase and causes DNA chain termination.
What is the difference between zanamivir and oseltamivir?
Z - inhaled powder
O - oral tablet prodrug
Describe the resistance that occurs in DNA polymerase inhibitors
resistance only develops in immunocompromised pts during prolonged therapy.
What is the spectrum of DNA polymerase inhibitors?
- treatment, prevention and suppression of HSV and VZV infection
- only ganciclovir is used for CMV infection
Describe the pharmacokinetics of DNA polymerase inhibitors.
- 15% of oral absorbed
- eliminated unchanged in urine
