Acyclovir

Aka: Acyclovir, Zovirax

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. Metabolized by Kidney
      1. Decrease interval in renal Impairment to q12-24h
   2. Dialysis: 50-100% dialyzable
3. Pregnancy and Lactation
   1. FDA Pregnancy Class C
   2. Safety unclear in Breast Feeding
4. How Supplied
   1. Tablets: 200, 400, 800 mg
   2. Suspension: 200 mg/5 ml
5. Dosing: Systemic Acyclovir
   1. General
      1. Base Weight calculations on Lean Body Mass
   2. HSV Encephalitis or Herpes Neonatorum
      1. Child: 30 mg/kg/day (1500 mg/m2/day) divided q8h IV
   3. Primary Herpetic Gingivostomatitis
      1. Adult: 200 mg PO q4 hours while awake (5x/day)
      2. Ped: 15 mg/kg/d (750 mg/m2/d) divide q8h IV x5-10 day
   4. Initial Genital HSV
      1. Adult: 200 mg PO 5 times per day for 10 days
   5. Episodic Genital HSV
      1. Adult: 200 mg PO 5 times per day for 5 days
   6. Prophylaxis of Genital HSV
      1. Adult: 400 mg PO bid for up to 12 months
   7. Herpes Zoster (Shingles) or Herpes Ophthalmicus
      1. Adult Oral: 800 mg PO 5 times/day for 7-10 days
      2. Adult IV: 10-12 mg/kg/dose q8 hours for 7-14 days
   8. Varicella Zoster Virus (Chicken Pox)
      1. Child
         1. Dose: 10-20 mg/kg/dose to 800 mg PO qid for 5 days
      2. Adult
         1. Dose: 600-800 mg/dose PO q4h while awake (5x/day)
         2. Dose: 1000 mg/dose PO q6h for 5 days
      3. Intravenous
         1. Dose: 30 mg/kg/day (1500 mg/m2/day) divided q8h IV
6. Dosing: Topical Acyclovir
   1. Initial genital HSV
      1. Apply to affected area 6 times per day for 7 days
7. Adverse Effects
   1. Headache
   2. Gastrointestinal Upset
   3. Impaired Renal Function
   4. CNS depression
      1. Lethargy
      2. Confusion
      3. Coma
   5. Tremors
   6. Agitation
8. Drug Interactions (prolong Acyclovir half life)
   1. Probenecid
   2. Zidovudine
9. Precautions
   1. Overdose may result in Renal Failure
   2. Maintain adequate urine to flush renal tubules
10. Efficacy: Herpes Labialis (Oral Herpes)
    1. Only effective if used at outset of symptoms
    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%