Acyclovir

Aka: Acyclovir, Zovirax, Sitavig

1. Indications
   1. Primary or Recurrent Herpes Simplex Virus Infection
      1. Oral Herpes (Herpes Labialis)
      2. Genital Herpes
   2. HSV Encephalitis
   3. HSV Keratitis
   4. Herpes Neonatorum
   5. Herpes Zoster
   6. Genital Herpes
   7. Varicella Zoster Virus (Chicken Pox)
   8. Herpes Zoster Ophthalmicus
   9. Herpes Labialis
2. Pharmacokinetics
   1. Base Weight calculations on Lean Body Mass
   2. Metabolized by Kidney
      1. Decrease interval in renal Impairment to q12-24h
   3. Dialysis: 50-100% dialyzable
3. Safety: Pregnancy and Lactation
   1. FDA Pregnancy Class C
   2. Safety unclear in Breast Feeding
4. Preparations
   1. Tablets: 200, 400, 800 mg
   2. Suspension: 200 mg/5 ml
   3. Buccal tablet (Sitavig)
5. Dosing: Orolabial Herpes (Cold Sores)
   1. Primary Herpetic Gingivostomatitis
      1. Adult: 200 mg orally every 4 hours while awake (5x/day)
      2. Ped: 15 mg/kg/day (750 mg/m2/day) divided five times daily for 5 days
   2. Episodic, recurrent Orolabial Herpes
      1. Topicals
         1. Acyclovir cream apply 5 times per day for 4 days
         2. Sitavig buccal one tablet per episode placed in upper gum on same side of mouth as symptoms
            1. Very expensive ($300 for 2 tabs in 2014) and only shortens Cold Sore course by <1 day
            2. (2014) Presc Lett 21(9): 53
      2. Systemic
         1. Child: 15 mg/kg (max: 200 mg) orally 5 times per day for 5 days
         2. Adult: 400 mg orally 3 times daily for 5 days (or 200 mg orally 5 times daily for 5 days)
6. Dosing: Herpes Neonatorum
   1. HSV Encephalitis or Herpes Neonatorum
      1. Child: 30 mg/kg/day (1500 mg/m2/day) divided every 8 hours IV
7. Dosing: Genital Herpes
   1. Initial Genital HSV
      1. Adult: 200 mg orally 5 times per day for 10 days
   2. Episodic Genital HSV
      1. Adult: 200 mg orally 5 times per day for 5 days
      2. Apply topical Acyclovir to affected area 6 times per day for 7 days
   3. Prophylaxis of Genital HSV
      1. Adult: 400 mg orally twice daily for up to 12 months
8. Dosing: Varicella Zoster
   1. Herpes Zoster (Shingles) or Herpes Ophthalmicus
      1. Adult Oral: 800 mg orally 5 times/day for 7-10 days
      2. Adult IV: 10-12 mg/kg/dose every 8 hours for 7-14 days
   2. Varicella Zoster Virus (Chicken Pox)
      1. Child
         1. Dose: 10-20 mg/kg/dose to 800 mg orally four times daily for 5 days
      2. Adult
         1. Dose: 600-800 mg/dose orally every 4 hours while awake (5x/day)
         2. Dose: 1000 mg/dose orally every 6 hours for 5 days
      3. Intravenous
         1. Dose: 30 mg/kg/day (1500 mg/m2/day) divided q8h IV
9. Adverse Effects
   1. Headache
   2. Gastrointestinal Upset
   3. Impaired Renal Function
   4. CNS depression
      1. Lethargy
      2. Confusion
      3. Coma
   5. Tremors
   6. Agitation
10. Drug Interactions (prolong Acyclovir half life)
    1. Probenecid
    2. Zidovudine
11. Precautions
    1. Overdose may result in Renal Failure
    2. Maintain adequate urine to flush renal tubules
12. Efficacy: Herpes Labialis (Oral Herpes)
    1. Only effective if used at outset of symptoms (first sense of Paresthesias such as burning or tingling)
    2. Shortens Vesicle life and decreases shedding
    3. Prevents recurrence in immunocompromised
    4. Reduction in episodes: 53%
    5. Quicker healing: 4 days instead of 8 for Placebo
    6. Reduction in number of Fever Blisters: 71%