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Acyclovir

Medical and Pharmacy Editor:

Brand Name: Zovirax

Generic Name: acyclovir

Drug Class: Antivirals, Other; Antivirals, HSV; Antivirals, VZV

What Is Acyclovir (Zovirax) and How Does It Work?

Acyclovir is approved by the Food and Drug Administration as a prescription drug that is commonly used as a topical, injectable, and oral treatment for genital herpes and cold sores. Herpes refers to a group of viruses that cause a variety of herpes infections including genital herpes, shingles, chicken pox (also chickenpox), cold sores, and encephalitis (inflammation of the brain). Herpes viral infections are very common. Genital herpes refers to a sexually transmitted disease (STD) that any sexually active person can contract and transmit.

Shingles and chicken pox are common skin conditions.Shingles and chicken pox are skin infections which are both caused by the herpes virus. They are not caused by the same virus that causes cold sores or genital herpes.

Many people who suffer from shingles or chicken pox (chickenpox) infection will experience symptoms such as a rash, often with pain, which is treatable with this drug.

Genital herpes is an STD caused by two types of viruses: herpes simplex type 1 and herpes simplex type 2. Most people with genital herpes do not know they have it. Still, symptoms often appear days to weeks after exposure. Symptoms of genital herpes generally include:

  • Flu-like symptoms such as fever, body aches, or swollen glands
  • Blisters, sores, or rash in the genital area with or without pain, itching, tingling
  • Blisters that pop open, causing painful sores.

Acyclovir may also help treat pain associated with an outbreak of genital herpes after the sores heal.

There is no cure for herpes, however, this prescription is a treatment that helps to decrease and ease symptoms of herpes infections.

Acyclovir is am antiviral drug that belongs to a class of medications called "antivirals," or "antiviral medications."

Your doctor may prescribe this drug as a treatment to relieve symptoms of your infection.

This medication is similar to the drug valacyclovir (Valtrex), which is another medication that may also be prescribed for herpes infections.

This drug may cause serious side effects or mild side effects. This includes side effects that may affect the liver. Side effects that affect the skin as well as allergic reactions have occurred.

Acyclovir is the generic equivalent of Zovirax.

Dosages

Adult and Pediatric Dosage Forms and Strengths

  • Injectable solution
    • 50 mg/mL
  • Oral suspension
    • 200 mg/5mL
  • Powder for injection
    • 500 mg/vial
    • 1 g/vial

Dosage Considerations – Should be Given as Follows:

Genital Herpes

  • Initial treatment: 200 mg orally every 4 hours while awake (5 times daily) for 10 days or 400 mg orally every 8 hours for 7-10 days
  • Intermittent treatment for recurrence: 200 mg orally every 4 hours while awake (5 times daily) for 5 days; initiate at earliest sign or symptom of recurrence
  • Chronic suppression for recurrence: 400 mg orally every 12 hours for up to 12 months; alternatively, 200 mg 3-5 times daily

Herpes Simplex Virus Encephalitis

10-15 mg/kg intravenously (IV) every 8 hours for 10 days; up to 14-21 days reported

Children 3 months to 12 years: 20 mg/kg IV every 8 hours for 10 days; up to 14-21 days reported

Children over 12 years: 10-15 mg/kg IV every 8 hours for 14-21 days

In obese patients, use ideal body weight (IBW)

Mucocutaneous Herpes Simplex Virus Infection

Treatment in immunocompromised patients (people with weakened immune systems)

  • Adult
    • Intravenous (IV): 5 mg/kg every 8 hours for 7 days; dosing up to 14 days reported
    • In obese patients, ideal body weight (IBW)
    • Oral (off-label): 400 mg every 4 hours while awake (5 times daily) for 7 days
  • Pediatric
    • Younger than 12 years: 10 mg/kg intravenously (IV) every 8 hours for 7 days
    • In obese patients, ideal body weight (IBW)
    • Older than 12 years: 5-10 mg/kg/day IV divided every 8 hours for 5-7 days; up to 14 days reported

Herpes Zoster (Shingles)

  • Adult
    • Acute treatment: 800 mg orally every 4 hours while awake (5 times daily) for 7-10 days
    • Immunocompromised patients
      • 10 mg/kg IV every 8 hours for 7 days
      • In obese patients, use ideal body weight (IBW)
      • CrCl 25-50 mL/min: Full recommended IV dose every 12 hours
      • CrCl 10-25 mL/min: Full recommended IV dose once daily
      • CrCl 0-10 mL/min: 50% of recommended IV dose once daily
  • Pediatric
    • Younger than 12 years (immunocompromised): 20 mg/kg IV every 8 hours for 7 days
    • In obese patients, use ideal body weight (IBW)
    • Older than 12 years (immunocompetent): 800 mg orally every 4 hours while awake (5 times daily) for 7-10 days
    • Older than 12 years (immunocompromised): 30 mg/kg/day IV divided every 8 hours for 7-10 days

Varicella Zoster (Chickenpox)

  • Adult
    • Greater than 40 kg (immunocompetent): 800 mg orally every 6 hours for 5 days
    • Immunocompromised patients: 10-15 mg/kg IV every 8 hours for 7-10 days
    • In obese patients, use ideal body weight (IBW)
  • Pediatric
    • Children 2 years and older and less than 40 kg: 20 mg/kg/dose orally every 6 hours for 5 days; not to exceed 800 mg/dose
    • In obese patients, use ideal body weight (IBW)
    • Greater than 40 kg: 800 mg orally every 6 hours for 5 days
    • Immunocompromised patients
  • Younger than 12 years: 20 mg/kg/dose intravenously (IV) every 8 hours for 7 days
  • Older than 12 years: 10 mg/kg/dose IV every 8 hours for 7 days

Dosing Modifications

  • Dose adjustment based on renal clearance and normal dosage regimen
  • 200 mg every 4 hours
    • 0-10 mL/min/1.73 m²: 200 mg every 12 hours
    • Greater than 10 mL/min/1.73 m²: 200 mg every 4 hours (five times daily)
  • 400 mg every 12 hours
    • 0-10 mL/min/1.73 m²: 200 mg every 12 hours
    • Greater than 10 mL/min/1.73 m²: 400 mg every 12 hours
  • 800 mg every 4 hours
    • 0-10 mL/min/1.73 m²: 800 mg every 12 hours
    • 10-25 mL/min/1.73 m²: 800 mg every 8 hours
    • Greater than 25 mL/min/1.73 m²: 800 mg every 4 hours (five times daily)

Dose adjustment based on dosage form

  • Renal impairment (IV)
    • CrCl 25-50 mL/min/1.73 m²: Give recommended dose every 12 hours
    • CrCl 10-25 mL/min/1.73 m²: Give recommended dose every 24 hours
    • CrCl less than 10 mL/min/1.73 m²: Give 50% of recommended dose every 24 hours
  • Renal impairment (Oral)
    • Normal dosage 200 mg every 4 hours or 400 mg every 12 hours and CrCl less than 10 mL/min/1.73 m²: Decrease to 200 mg every 12 hours
    • Normal dosage 800 mg every 4 hours and CrCl 10-25 mL/min/1.73 m²: Decrease to 800 mg every 8 hours
    • Normal dosage 800 mg every 4 hours and CrCl less than 10 mL/min/1.73 m²: Decrease to 800 mg every 12 hours

What Are Side Effects Associated with Using Acyclovir (Zovirax)?

Common side effects or health problems may include:

Other acyclovir side effects, adverse reactions, or health problems may include:

This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Acyclovir (Zovirax)?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of this medicine or any drug before seeking medical advice from your doctor, healthcare provider or pharmacist first. To do so may result in serious consequences or side effects.

Severe Interactions of Acyclovir include:

  • There are no severe interactions from the use of acyclovir.

Serious Interactions of Acyclovir include:

  • amphotericin B deoxycholate
  • bacitracin
  • cidofovir
  • neomycin PO
  • oral probenecid
  • talimogene laherparepvec

Acyclovir has moderate interactions with at least 28 different drugs.
Acyclovir has mild interactions with at least 65 different drugs.
This document does not contain all possible interactions from the use of this medication. Therefore, before using this drug, tell your doctor or pharmacist of all the drugs you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Acyclovir (Zovirax)?

Warnings

  • This medication contains acyclovir Do not take Zovirax if you are allergic to acyclovir or any ingredients contained in this drug
  • Keep this medication and all drugs out of reach of children In case of overdose, get medical help or contact a Poison Control Center immediately

Contraindications

  • Hypersensitivity

Effects of Drug Abuse

  • There are no effects of drug abuse from the use of acyclovir

Short-Term Effects

  • See "What Are Side Effects Associated with Using Acyclovir (Zovirax)?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Acyclovir (Zovirax)?"

Cautions

Pregnancy and Lactation

  • Acyclovir may be acceptable for use during pregnancy
  • Either animal studies show no risk but human studies are not available, or animal studies showed minor risks and human studies were done and showed no risk
  • Acyclovir enters breast milk; use with caution if breastfeeding
Reviewed on 4/14/2017


SOURCE:
Medscape. Acyclovir.
https://reference.medscape.com/drug/zovirax-acyclovir-342601
REFERENCE:
DailyMed. Acyclovir.
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=cb64dfab-52ee-4312-bc9c-c3d04efe9109

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