Part 7 Antivirals

Antiviral Agents

Chapter 8: Part 2

HSV Recap
  • Highly Contagious: HSV is highly contagious when lesions are open.
  • Education & Re-Appointment: Patients should be reappointed and educated regarding the transmissibility of HSV.
  • HSV Types:
    • HSV 1: Primarily causes oral infections.
    • HSV 2: Primarily responsible for genital infections.
  • Initial Infections:
    • Often present as primary herpetic gingivostomatitis, usually observed in infants and children.
  • Recurrent Infections:
    • Commonly leads to "cold sores" or herpes labialis, which are self-limiting lesions.
    • Typically heal without intervention in 10-14 days.
    • Antivirals can support patient relief, and some patients may take antiviral medication prophylactically.
Antiviral Agents
  • Herpes Simplex Virus (HSV) is the primary focus.
  • Common Antiviral Agents:
    • Acyclovir
    • Docosanol 10%
    • Penciclovir
    • Famciclovir
Acyclovir
  • Classification: A purine nucleoside that acts by inhibiting DNA replication.
  • Spectrum of Action:
    • Effective against:
    • HSV 1 and 2
    • Epstein-Barr Virus
    • Varicella-zoster Virus
    • Cytomegalovirus
Adverse Reactions of Acyclovir
  • Topical Application:
    • Symptoms of burning, stinging, or mild pain.
  • Oral Use:
    • Headache: Most common side effect.
    • CNS Effects: Includes vertigo, dizziness, fatigue, irritability.
    • Gastrointestinal (GI) Effects: Nausea, vomiting, diarrhea, anorexia, a funny taste, acne, accelerated hair loss, menstrual abnormalities, and other effects.
Dental Uses of Acyclovir
  • Topical Form: Limited to treating non-life-threatening initial and recurrent mucocutaneous herpes simplex virus 1 (HSV-1) and HSV-2 in immunocompromised patients.
  • Effectiveness:
    • Not proven effective for immunocompetent patients.
    • Many patients use it nonetheless, but it does not prevent transmission or recurrence.
  • Oral Dosage:
    • Immunocompetent: 200 mg five times daily (every 4 hours) for 5 days.
    • Immunocompromised: 400 mg five times daily (every 4 hours) for 5 days.
Docosanol 10%
  • Brand Name: Abreva.
  • Availability: Topical and over-the-counter (OTC) without a prescription.
  • Efficacy: Reduces healing time by half a day when used within 12 hours of prodromal symptom onset (before lesion appearance). Symptoms can include itchiness, tingling, stinging, and burning, which are warning signs of an impending outbreak.
Penciclovir
  • Form: Available topically.
  • Efficacy:
    • Reduces both the duration of lesions and associated pain for primary and recurrent HSV infections of the lips and face.
  • Advantages Over Acyclovir:
    • Achieves higher concentrations within cells.
    • Duration of action within cells is longer, providing extended efficacy.
Famciclovir and Valacyclovir
  • Classification: Prodrugs converted to penciclovir and acyclovir, respectively.
  • Efficacy:
    • Famciclovir is more effective than penciclovir.
    • Valacyclovir is more effective than acyclovir.
  • Uses:
    • Treatment of recurrent episodes of genital herpes.
    • Treatment of acute localized varicella-zoster infections.
  • Intravenous Ganciclovir: IIndicated for serious cytomegalovirus (in the herpes family) retinitis in immunocompromised patients.
Long-Term Suppressive Antiviral Therapy
  • Chronic Treatment: Patients may be prescribed long-term antivirals for HSV.
  • Common Drugs: Include acyclovir, famciclovir, and valacyclovir.
  • Recommendation: Suggested for patients experiencing frequent herpetic recurrences.
Antiviral Agents for Herpes Simplex Virus 1

  • Drugs and Routes:

    • Acyclovir (Zovirax): Oral (PO), topical, intravenous (IV).
    • Famciclovir: Oral (PO).
    • Valacyclovir (Valtrex): Oral (PO).
    • Penciclovir (Denavir): Topical.
    • Docosanol (Abreva): Topical.

  • Indications:

    • Primary and recurrent herpes in both immunocompromised and immunocompetent patients.

  • Adverse Effects:

    • Local reactions for topical agents include burning, erythema, and pruritus; oral agents may cause nausea and CNS effects.
HSV Considerations
  • Corticosteroids: Not recommended in viral infections as they increase susceptibility to infections and mask symptoms.
  • Dental Treatment: Patients with active herpetic lesions should be rescheduled for non-elective dental treatment due to the risk of spreading the virus.
  • Counseling: Important to provide thorough counseling to patients about HSV.
Viral Life Cycle Summary
  1. Attachment: Virus attaches to a specific host cell surface by binding to specific receptors.
  2. Entry: The virus enters the host cell, either by merging with the cell membrane or being engulfed by the cell.
  3. Replication: Inside the host, the virus releases its genetic material (DNA or RNA); this genetic material commandeers the