Acyclovir

General

• Type: Antiviral: nucleoside analoge
• Dosage Forms: IV, PO (200 mg, 400 mg, and 800 mg)
• Common Trade Names: Zovirax

Adult Dosing

• HSV Encephalitis
  • 10mg/kg IV q8h x 10 d

• Genital/Mucocutaneous HSV
  • Immunocompetent
    • 1st episode, Mild-mod: 400mg PO TID x 7-10 d
    • 1st episode, Severe: 5-10mg/kg IV q8h x 2-7 d
    • Recurrence: 400mg PO TID x 5 d
    • Suppression: 400mg PO BID
  • Immunocompromised
    • 1st episode: 400mg PO TID x 5-10 d
    • Recurrence: 400mg PO TID x 5-10 d
    • Suppression: 400-800mg PO BID-TID

• Varicella
  • Immunocompetent
    • 800mg PO QID x 5-7 d
  • Immunocompromised
    • 10mg/kg IV q8h x 7 d
• Herpes Zoster
  • Immunocompetent
    • 800mg PO 5x/day x 7 d
  • Immunocompromised
    • 10mg/kg IV q8h x 7 d

• Herpes Zoster
  • Immunocompetent
    • 800mg PO 5x/day x 7 d
  • Immunocompromised
    • 10mg/kg IV q8h x 7 d

• Herpes zoster ophthalmicus
  • 800mg PO 5x/day x 7 d

• HSV prophylaxis in immunocompromised
  • 400-800mg PO BID-TID

• HSV keratitis
  • 400mg PO 5x/day

Indications by Disease

Disease	Dose	Context
Bell's palsy	400mg 5x per day x1 week	Antiviral
Encephalitis	10mg/kg (10-15mg/kg for pediatrics) every 8hrs	HSV
Herpes Simplex Virus-2	400mg PO q8hrs x 7-10 days or 200mg PO 5x/day x 7-10 days	Initial Episode
Herpes Simplex Virus-2	400mg PO q8hrs x 5 days or 800mg PO q12hrs x 5 days or 800mg PO q8hrs x 2 days	Recurrence
Herpes Simplex Virus-2	400mg PO q12hrs daily	Suppressive
Herpes gingivostomatitis	400 mg PO 5x/day (q4hrs while awake) x 5 days	Normal host
Herpes gingivostomatitis	5 mg/kg IV q8h x 7 days	Immunocompromised
Herpes gingivostomatitis	400mg PO 5x/day x 14-21 days	Immunocompromised (oral)
Herpes labialis	400 mg PO 5x/day (q4hrs while awake) x 5 days	Normal host
Herpes labialis	5 mg/kg IV q8h x 7 days	Immunocompromised
Herpes labialis	400mg PO 5x/day x 14-21 days	Immunocompromised (oral)

Pediatric Dosing

• Neonatal HSV
  • 40-60mg/kg/day IV divided q12h x 14-21 d
• HSV encephalitis
  • 3 mo - 11 y/o
    • 30-45mg/kg/day IV divided q8h x 14-21 d
  • >12 y/o
    • 30mg/kg/day IV divided q8h x 14-21 d
• Genital/mucocutaneous HSV
  • Immunocompetent
    • 1st episode, 2-11 y/o
      • 40-80mg/kg/day PO divided q6-8 h x 5 d, max 1g/day
    • 1st episode, >12 y/o
      • 1g/day PO divided 5x/day x 7-10 d
  • Immunocompromised
    • PO: >2 y/o: 1g/day PO divided 3-5x/day x 7-14 d
    • IV: >1 y/o: 30mg/kg/day IV divided q8h x 7-14 d
• Varicella
  • Immunocompetent
    • PO: > 2 y/o: 80mg/kg/day PO divided q6h x 5 d
    • IV: > 1 y/o: 30mg/kg/day IV divided q8h x 7-10 d
  • Immunocompromised
    • 30mg/kg/day IV divided q8h x 7-10 d
• Herpes zoster
  • Immunocompetent
    • PO: > 12 y/o: 4g/day PO divided 5x/day x 5-7 d
    • IV: 30mg/kg/day IV divided q8h x 7-10 d
  • Immunocompromised
    • 30mg/kg/day IV divided q8h x 7-10 d
• HSV-1/Herpes labialis
  • 15 mg/kg PO (max dose of 200 mg) 5 times per day

Indications by Disease

Disease	Dose	Context
Encephalitis	20mg/kg IV q8hrs x 21 days (neonates); 10-15mg/kg IV q8hrs x 14-21 days (children)	Pediatric HSV
Herpes gingivostomatitis	40-80mg/kg PO divided in 3-4 doses for 5-7 days	Normal host
Herpes labialis	40-80mg/kg PO divided in 3-4 doses for 5-7 days	Normal host
Neonatal conjunctivitis	20mg/kg IV q8h x 14-21 days	Herpetic conjunctivitis
Pediatric fever of uncertain source	20mg/kg/dose	Neonatal 0-28 days if HSV suspected

Special Populations

• Pregnancy Rating: B
• Lactation Risk Categories: Safe
• Renal Dosing
  • Adult
    • IV
      • CrCl 25-50 give q12h
      • CrCl 10-24 give q24h
      • CrCl <10 decrease dose 50%, give q24h
      • HD give usual dose as supplement
      • PD no supplement
    • PO
      • CrCl <25: see package insert
      • HD: give usual dose as supplement
      • PD: no supplement
  • Pediatric
  • Geriatric
    • Refer to adult dosing. Oral: Initial doses should begin at the low end of the dosage range
• Hepatic Dosing
  • Not defined

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Hallucinations / psychosis
• Seizure
• Coma
• Encephalopathy
• Thrombocytopenia
• Leukopenia
• Anaphylaxis
• Angioedema
• Erythema Multiforme
• SJS / TEN
• TTP
• Hepatitis
• Renal failure

Common

• Nausea/vomiting/diarrhea
• Headache
• Dizziness
• Rash
• Arthralgia
• Confusion / lethargy
• Elev. BUN/creatinine
• Photosensitivity

Pharmacology

• Half-life: 2.5 - 3.3 hrs
• Metabolism: virally infected cells (intracellularly); liver
• Excretion: Urine
• Mechanism of Action: Inhibits DNA polymerase

References

• Epocrates 2015
• Acetazolamide injection [prescribing information]. Big Flats, NY: X-Gen Pharmaceuticals, Inc; October 2015.
• Acetazolamide tablets [prescribing information]. Hawthorne, NY: Taro Pharmaceuticals; September 2013.