Antiviral Treatmen Flashcards
How do antivirals work?
What are the two approaches of antiviral therapy?
- Approach 1 – Directly Acting Antivirals / Small Molecule Inhibitors
- Approach 2 – Immunomodulators:
How do the directly acting antivirals/small molecule inhibitors work? What do they target?
- Viruses encode proteins for… cell entry, genomic replication/transcription, assembly and release of progeny
- E.G. nucleic acid polymerases, proteases, integrase CCR5, terminase
- These proteins are a target for AV-drugs (e.g. protease inhibitors, polymerase inhibitors, integrase inhibitors)
- SMIs / DAAs block production/action of the above inhibit viral replication or action
How do immunomodulators work?
- Viral replication is detected by PRRs (i.e. TLRs, RIG-like receptors) trigger innate immune responses
- This antiviral immune response can be boosted by giving immunomodulators
- E.G. interferon (tx HBV, HCV), IVIG (viral pneumonitis), imiquimod (HPV), steroids (HSE)
What are the limiting factors of antiviral therapy?
- Limiting factors of antiviral therapy:
- The natural host immune response is critical; difficulties in treating:
- Transplant patients
- HIV patients
- Adherence to treatment
- Antiviral drug resistance
- Drug toxicity and interactions
- The natural host immune response is critical; difficulties in treating:
How do we classify herpesvirus?
What are the stages of herpes infection?
- Primary infection (e.g. chickenpox)
- Latency - e.g. in dorsal root ganglia
- Reactivation e.g. zoster-shingles
What causes chickenpox? What are the complications?
- Caused by primary infection with varicella-zoster virus (VZV)
- Uncomplicated in children
- Susceptible to complications in adults (e.g. pneumonitis)
- Severe disease in immunocompromised
What is zoster? What does it cause I the immuncompetent and immunocompromised?
- •Reactivation of latent infection (dorsal root ganglia)
-
Immunocompetent
- Dermatomal distribution
- Complication: Post-herpetic neuralgia
-
Immunocompromised
- Can experience multidermatomal or disseminated infection with severe complications
What is a prodrug?
A prodrug is an inactive precursor of a drug, that is metabolized into the active form within the body.
What antivirals used for the treatment of HSV and VZV?
What is the MOA of acyclovir?
AKA ‘chain terminators’
What does acyclovir require in order to be activated? How does It have selective activity?
How do we treat HSV encephalitis?
- Immediate empirical treatment IV Aciclovir 10mg/kg TDS (without waiting for test results)
- I.E. 700mg TDS (for 70kg person)
- If confirmed, treat for 14-21 days
- I.E. 700mg TDS (for 70kg person)
- Should do a repeat LP before stopping abx
What are the indications for tx of VZV?
- Chickenpox in adults (risk of pneumonitis)
- Zoster in adults >50 years (risk of post-herpetic neuralgia)
- Primary infection or reactivation in an immunocompromised patient
- Neonatal chickenpox
- If increased risk of complications (e.g. underlying lung disease, eye involvement)
What are the stages of CMV virus?
- Primary infection → latent in blood monocytes and dendritic cells → reactivated e.g. following immunosuppression
Where would CMV be in asymptomatic patients?
Shed in asymptomatic patients via saliva, urine, semen and cervical
What are the consequences of CM infection in the immunocompromised
- Bone marrow suppression
- Retinitis
- Pneumonitis
- Hepatitis
- Colitis
- Encephalitis
CMV pneumonitis
Widespread retinal exudate and haemorrhage - CMV
Owl’s eye inclusions - CMV
What are the MCV antiviral drugs? What route are they given by?
- 1st line Gangciclovir (GCV) - IV
- Prodrug: Valganciclovir (VGC) - PO
- 2nd line Foscarnet (FOS) - IV/intravitreal
- 3rd lie Cidofovir (CDV) - IV
Letermovir - recently approved
How does gangciclovir get activated?
How do (val/)gangciclovir work? What does it have activity against? How is it excreted? What are the indication? What are the side effects and contraindications?
How does foscarnet work? What is it effective against? How is it given? What are the indications? What are the SEs?
How does cidofivir work? What is it active against? How is ti administered= What is the indications and side effects?
What are the strategies for Treatment of CMV in Transplant Patients?
- (A) TREAT established disease (GCV and reduce immunosuppression) – high mortality in HSCT
-
(B) PROPHYLAXIS with GCV/vGCV
- Indication: solid organ transplant (i.e. renal)
- SEs: bone marrow toxicity
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(C) Best - PRE-EMPTIVE THERAPY with Foscarnet > GCV/vGCV
- Indication: HSCT
- Twice weekly monitoring for the appearance of CMV on PCR in the blood