What is this medication?
Officially indicated to treat herpes simplex virus (HSV), herpes zoster (shingles), and varicella (chickenpox).
How does this medication work?
Acyclovir/Zovirax is converted to acyclovir monophosphate by virus-specific thymidine kinase then further converted to acyclovir triphosphate by other cellular enzymes. Acyclovir triphosphate inhibits DNA synthesis and viral replication by competing with deoxyguanosine triphosphate for viral DNA polymerase and being incorporated into viral DNA.
How should I take this medication?
Herpes Simplex Virus (HSV), Central Nervous System Infection (Encephalitis or Meningitis)
IV: 10 mg/kg/dose every 8 hours. Duration for encephalitis is 14 to 21 days and for meningitis is 10 to 14 days; treatment of encephalitis requires IV therapy while treatment of meningitis may include step-down oral antiviral therapy.
Herpes Simplex Virus (HSV), Genital
Oral (Initial): Take 400 mg 3 times daily or 200 mg 5 times daily for 7 to 10 days; extend duration if lesions have not healed completely after 10 days.
Oral (Recurrent Episode): Take 400 mg 3 times daily for 5 days or 800 mg twice daily for 5 days or 800 mg 3 times daily for 2 days.
Oral (Suppressive Therapy): Take 400m twice daily
Herpes Simplex Virus (HSV), Orolabial
Oral: Take 400 mg 3 times daily for 5 to 10 days and until complete lesion resolution in immunocompromised patients.
Herpes Zoster (Shingles)
Oral: Take 800 mg 5 times daily for 7 days. Initiate at earliest sign or symptom; treatment is most effective when initiated ≤72 hours after rash onset but may initiate treatment >72 hours after rash onset if new lesions are continuing to appear.
Oral: initiate therapy within 24 hours of symptom onset but may start later if the patient still has active lesions. Take 800 mg 5 times daily for ≥5 to 7 days and until all lesions have crusted.
What should I watch for while using this medication?
Can cause signs/symptoms of neurotoxicity (i.e. tremor, myoclonus, confusion, agitation, lethargy, impaired consciousness)
Use with caution in patients with renal impairment
Thrombotic microangiopathy has bee reported
What if I miss a dose?
If you miss a dose of medication, try to take it as soon as possible. However, if it is almost time for your next dose, take only that scheduled dose. Do not take double or extra doses.
How should I store this medication?
Keep out of the reach of children at all times. Store at room temperature, 59 to 86° F (15 to 30° C). Protect from light. Keep the container tightly closed. Properly dispose of any unused medication after the expiration date.
What are the possible side effects of using this medication?
The frequency of side effects is not defined, dependent upon the dose, duration, concomitant therapy and dosage form:
Central nervous system: Malaise (oral: 12%)
Hematologic & oncologic: Decrease in absolute neutrophil count (neonates: 3% to 16%), decreased hemoglobin (neonates: 13%)
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