Sweatman - Antivirals Flashcards
How do you prevent and treat Influenza A and B?
What are the adverse effects?
- Treatment: Oseltamivir (PO), Zanamivir (inhalation)
- Prevention: vaccines (inactivated, live), Oseltamivir, Zanamivir
- NOTE: just influenza A virus tx = Amantadine (PO) or Rimantadine (PO)
- AE for oseltamivir: Minimal adverse effects
Potential for fatal neuropsychiatric adverse effects in flu patients; serious skin reaction reported rarely - AE for zanamivir: Headache, throat/tonsil pain, cough, viral infection. NOT to be used w/underlying pulmonary disease – fatal bronchospasm!
How do you differentiate between viral and bacterial pneumonia?
_**Viral PNA_
- Usually youngsters under 5 yoa
- Typically associated with an ongoing epidemic
- The onset of illness is slow
- Common symptoms include rhinitis & wheezing
- WBC usually < 10x10^9/L; CRP < 20mg/L; CXR - sole bilateral interstitial infiltrates
- Response to Abx tx is slow or non-responsive
_**Bacterial PNA_
- Usually adults
- Rapid onset of illness
- Symptoms include high fever and tachypnea
- WBC >15; CRP > 60; CXR - lobar alveolar infiltrates
- Response to abx treatment is rapid
Do do oseltamivir and zanamivir work - what is their mechanism of action?
Potent sialic acid analogues causing a conformational change for the active sites of neuraminidase enzymes of influenza A and B
This inhibits the release of progeny virus from the cell surface and limits spread of virus in body.
What is the mechanism of action of amantadine and rimantadine? What are these drugs used to treat?
What are the adverse effects/toxicities?
- Block the uncoating of the influenze virus after endocytosis of the virion.
- How, you ask?
- The endosome containing the virion is acidfied by H+ATPase and the virion must be acidfied as well via M2 ion channels. Amantadine and Rimantadine block the M2 ion channel so the virion cannot become acidified –> virion cannot uncoat
Used to treat Influenza A virus (Sweatman) but according to First Aid, these drugs are considered “not useful” becaue of increased resistance
-Toxicity: Multiple adverse effects including neurologic, nausea & orthostatic hypotension. Contraindicated in narrow angle glaucoma and with breastfeeding
What drug(s) are used to treat respiratory syncytial virus (RSV)?
How do you prevent RSV or prevent its progression?
Ribavirin (IV or inhalation) - what is its MOA?
- Inhibits synthesis of guanine nucleotides by competitive inhibition; This drug is mostly used for HCV
Prevention is via palivizumab and this is the preferred treatment especially for children
What is the mechanism of action of Ribavirin?
What is this drug used to treat?
What are the adverse effects?
- Inhibits synthesis of guanine nucleotides by competitive inhibition; This drug is mostly used for HCV but it is also used to treat RSV
Remember, the preferred tx in children with RSV is palivizumab
- AE: Many common adverse effects, most commonly fatigue, headache, myalgia, nausea, fever
- *BLACK BOX warnings for hemolytic anemia & M/F teratogenicity**
What is the MOA of palivizumab? What is this drug used to treat?
palivizumab (Synagis) is a monoclonal antibody that targets the F protein of RSV preventing fusion to cell thereby inhibiting entry into the cell and preventing infection
How do you treat adenovirus? What is the mechanism of action of this drug?
How do you prevent adenovirus?
What are the adverse effects of this drug treatment?
Cidofovir - inhibits viral DNA polymerase by competing for incorporation into viral DNA (does not require phosphorylation by viral kinase)
- Prevention: Vaccine against types 4 & 7
- Multiple adverse effects including neurologic, hematologic & tubular damage
BLACK BOX warning for renal impairment/toxicity
What would you prescribe for rhinovirus infection?
A bitchslap…
Supportive care, bitch. Do not give them an antibiotic
How do you treat Human metapneumovirus ?
ribavirin
How do you treat hantavirus?
ribavirin
How do you treat varicella-zoster virus? What are the MOA of these drugs?
How do you prevent varicella-zoster virus?
Describe the metabolism of each drug?
What are toxicities of each drug?
Acyclovir (IV) and Valacyclovir (PO)
- MOA: causes chain termination by acting as a guanosine analog; valacyclovir is a prodrug of acyclovir
- Prevent with vaccine
- Viral cells transform acyclovir to its active triphosphate form. Systemic elimination unchanged by glomerular filtration and tubular secretion
- Headache, nausea, elevated hepatic enzymes, nasopharyngitis, neutropenia. Maintain hydration to prevent renal precipitation
Use cautiously in renal impairment or with reno-toxic drugs
