Podcast
Questions and Answers
What is the main mechanism of action of Foscarnet?
What is the main mechanism of action of Foscarnet?
Which of the following is a key advantage of Foscarnet over acyclovir and ganciclovir?
Which of the following is a key advantage of Foscarnet over acyclovir and ganciclovir?
What is the primary indication for Famciclovir use?
What is the primary indication for Famciclovir use?
How does the bioavailability of Famciclovir compare to Penciclovir?
How does the bioavailability of Famciclovir compare to Penciclovir?
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Which of the following is a common adverse effect associated with Foscarnet?
Which of the following is a common adverse effect associated with Foscarnet?
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What is the primary mechanism of action of Penciclovir?
What is the primary mechanism of action of Penciclovir?
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Which of the following is a key advantage of Valganciclovir over Ganciclovir?
Which of the following is a key advantage of Valganciclovir over Ganciclovir?
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Which of the following viruses is Aciclovir primarily used to treat?
Which of the following viruses is Aciclovir primarily used to treat?
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What is the primary advantage of Famciclovir over Aciclovir for the treatment of recurrent herpes labialis?
What is the primary advantage of Famciclovir over Aciclovir for the treatment of recurrent herpes labialis?
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Which of the following is a common adverse effect associated with Penciclovir?
Which of the following is a common adverse effect associated with Penciclovir?
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Study Notes
Antivirals for Herpes Viruses
- Valaciclovir: prodrug of aciclovir, improved bioavailability (54-70%), converted to aciclovir by cellular enzymes
- Indications: herpes zoster virus (shingles), acute genital HSV, prevention and treatment of recurrent herpes genitalis, mucocutaneous HSV
- A/E: oral (nausea, vomiting, diarrhea, headache), I.V (nephrotoxic, reversible, phlebitis at injection site), topical (burning, stinging)
Ganciclovir and Valganciclovir
- Ganciclovir: aciclovir analogue, inhibits viral DNA replication, 100x more active against cytomegalovirus (CMV) than aciclovir
- Valganciclovir: prodrug of ganciclovir, poor oral bioavailability, converted to ganciclovir by intestinal and hepatic esterases
- Activity against HSV and VZV: equal to aciclovir
Penciclovir
- Similar to acyclovir, but only topical
- MOA: penciclovir triphosphate inhibits herpes DNA synthesis by acting as a false substrate for viral DNA polymerase
- Indication: treatment of recurrent orolabial herpes simplex
Herpes Simplex Virus (HSV)
- HSV1: oral herpes (cold sores)
- HSV2: genital herpes
- Herpes Zoster Virus (HZV): shingles
- Varicella Zoster Virus (VZV): chicken pox
Aciclovir
- Guanosine derivative (nucleoside analogue)
- Prodrug: activated in infected cells
- MOA: aciclovir triphosphate (active form) incorporated into viral DNA, irreversibly inhibits viral DNA polymerase
- Indications: treatment of HSV (I & II), varicella zoster virus, prophylaxis of recurrent episodes (>6/year) of herpes genitalis
- PK: T1/2 = 2-3hrs, 10-30% orally bioavailable, renally eliminated
Famciclovir
- Diacetyl 6-deoxy analogue of penciclovir
- Oral indications: CMV retinitis prophylaxis and treatment in immunocompromised patients, prevention of CMV infections in organ transplant patients
- A/E: myelosuppression, neutropenia, thrombocytopenia
- Rapidly absorbed, 77% bioavailability, metabolized into penciclovir, excreted renally as penciclovir and its 6-deoxy precursor
Foscarnet
- Non-nucleoside DNA polymerase inhibitor
- MOA: direct inhibition of DNA polymerase, not incorporated into the growing viral DNA
- Active against herpes, varicella, and CMV, including those resistant to acyclovir and ganciclovir
- A/E: nephrotoxicity
Antivirals for Hepatitis
- Interferons (IFNs): immunomodulator/biological agents, produced in lab by rDNA technology
- Indications: treatment of chronic Hepatitis B and C
- Other antiviral drugs for hepatitis: Ribavirin, Entecavir, Tenofovir, Emtricitabine, Lamivudine
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Description
Test your knowledge on severe herpes infections, disseminated herpes infections, and the antiviral medication used to treat them, including valaciclovir. Learn about indications, dosages, and potential adverse effects.
