Antivirals Flashcards
What are viruses made of?
Protein coat (capsid)
nucleic acid core, genome
some have lipoprotein envelope
What makes viruses antigenic?
the lipoprotein evelope
*viruses are obligate intracelluar parasites
What are the two mechanisms antiviral agents need?
Either:
- block viral entry into or exit from the cell
- be active inside the host cell
to inhibit active replcation
Do antiviral agents eliminate non-replicating or latent viruses?
No
- a virus has to be actively replicating for an antiviral drug to be effective.
- effective host immune response remains essential for the recovery from the viral infection
What are the anti-HSV/VZV agents?
acyclovir (zovirax)
famcyclovir (famvir)
valacyclovir (valtrex)
- all guanine nucleoside analogs that inhibits viral DNA-polymerase
- only actively replicating viruses are inhibited
What is the treatment of choice for HSV genital infections, orolabial, HSV encephalitis, HSV infection in immunocompromised and pregnant pts?
Acyclovir!
Acyclovir
- distribution
- excretion
- routes of admin
- pregnancy/lactation
- all body tissues and CNS
- renal excretion
- Topical, oral, IV
- Category B pregnancy, safe for lactation
How does acyclovir selectively destroy cells?
It is a prodrug that enters all cell and only becomes activated in herpes infected cells by phosphorylation. Uninfected cells do not phosphorylate acyclovir.
Acyclovir
-adverse effects
- GI sx
- HA
- rash
- photosensitivity
- anemia
- reversible renal toxicity (crystallization in the renal tubules)
- Neuro sx (somnolence, hallucinations, coma, confusion)
- TTP/HUS
Famciclovir
- routes of administration
- metabolism
- excretion
- pregnancy/lactation
- mechanism
- orally only
- first pass metabolism in intestine and live results in conversion to pencyclovir
- renal excretion
- Pregnancy cat B, lactation: safety unknown
- mechanism is similar to acyclovir (taken up in an infected cell and phosphorylated to the active form)
Famcyclovir
-adverse effects
- GI sx
- HA
- Fatigue
- abnormal LFTs
- neutropenia
- thrombocytopenia
- neuro sx (somnolence, hallucinations, delirium)
Valacyclovir
- Mechanism
- exceretion
- routes of admin
- advantage
- disadvantage
- preg/ lactation
- It is a prodrug of acyclovir, undergoes rapid first pass metabolism to yeild acyclovir
- renal excretion (>50%)
- Oral, food does not affect absoption
- better oral bioavailbility, more conveinent dosing
- more pricey
- Pregnancy cat B, lactation: safe
Valcyclovir
-Adverse effects
- GI sx
- HA
- rash
- photosensitivity
- elevated LFTs
- Reversible renal toxicity
- neuro sx
- TTP/HUS
What is the drug of choice for HSV Keratoconjunctivitis?
Trifluridine (Viroptic)
-dendritic lesion in eye
What is the drug of choice for CMV retinitis in immunocompromised patients and prevention of CMV disease in transplant patients?
Ganciclovir (Cytovene)
Ganciclovir
- routes of admin
- excretion
- pregnancy/ lactation
- adverse effects
- Oral, IV, intraocular
- renal (>90%, unchanged)
- Preg cat C, lactation: unsafe
AE -reversible pancytopenia -fever rash -phlebitis -confusion -renal dysfunction -psych disturbances -seizures
What is essential for the replication of the influenza virus?
enzyme neuraminidase is essential for replication
What are the neurominidase inhibitors and how do they work?
Oseltamivir
Zanamavir
-prevent the release of new virons and their spread from cell to cell
can be used for both prophylaxis and acute treatment
Zanamivir
- routes of admin
- adverse effects
- inhalation
- nasal and throat discomfort, bronchospasm
Amantadine and Rimantadine
Adverse effects
Why are they not currently recommended in the US?
- Seizures
- anticholinergic
- CNS
- edema
- blurry vision
-too much resistance!
Ribavirin is the drug of choice for?
alternative for?
-RSV bronchiolitis and pneumonia in hospitalized children, lassa fever
alternative for: influenza, para influenza, measles, HCV
Ribavirin
routes of admin
preg/ lacation
adverse effects
- Orally and inhalation (IV from CDC)
- Preg cat X, latation: probably unsafe
AE
- BBW- hemolytic anemia
- resp deterioration
- depression
- suicidal ideation
- psych issues
- anxiety
- fatigue
- dizziness
How do you get:
Hep A
Hep B
Hep C
A: oral-fecal route, clears on its own
B: sex, needles, may clear on its own (may be chronic)
C: most likely to cause permanent damage. same stuff
Standard treatment for Hep C?
SE?
Ribavarin plus interferon
SE: severe flu like sx fatigue depression anemia
