Acyclovir Oral Suspension

Name: Acyclovir Oral Suspension

Acyclovir Oral Suspension Description

Acyclovir is a synthetic nucleoside analogue active against herpesviruses. Acyclovir Suspension is a formulation for oral administration.

Each teaspoonful (5 mL) of Acyclovir Suspension contains 200 mg of acyclovir and the inactive ingredients methylparaben 0.1% and propylparaben 0.02% (added as preservatives), carboxymethylcellulose sodium, flavor, glycerin, microcrystalline cellulose, and sorbitol.

Acyclovir is a white, crystalline powder with the molecular formula C8H11N5O3 and a molecular weight of 225. The maximum solubility in water at 37°C is 2.5 mg/mL. The pka’s of acyclovir are 2.27 and 9.25.

The chemical name of acyclovir is 2-amino-1,9-dihydro-9-[(2-hydroxyethoxy) methyl]-6H-purin-6-one; it has the following structural formula:

Acyclovir Oral Suspension - Clinical Pharmacology

Pharmacokinetics: 

The pharmacokinetics of acyclovir after oral administration have been evaluated in healthy volunteers and in immunocompromised patients with herpes simplex or varicella-zoster virus infection. Acyclovir pharmacokinetic parameters are summarized in Table 1.

Table 1. Acyclovir Pharmacokinetic Characteristics (Range)
Parameter Range
  Plasma protein binding 9% to 33%
  Plasma elimination half-life 2.5 to 3.3 hr
  Average oral bioavailability 10% to 20%*

*Bioavailability decreases with increasing dose.

In one multiple-dose, crossover study in healthy subjects (n = 23), it was shown that increases in plasma acyclovir concentrations were less than dose proportional with increasing dose, as shown in Table 2. The decrease in bioavailability is a function of the dose and not the dosage form.

Table 2. Acyclovir Peak and Trough Concentrations at Steady State
Parameter 200 mg 400 mg 800 mg
Css max  0.83 mcg/mL 1.21 mcg/mL 1.61 mcg/mL
Css trough 0.46 mcg/mL 0.63 mcg/mL 0.83 mcg/mL

There was no effect of food on the absorption of acyclovir (n = 6); therefore, Acyclovir Suspension may be administered with or without food.

The only known urinary metabolite is 9-[(carboxymethoxy)methyl]guanine.

Special Populations:

Adults With Impaired Renal Function:

The half-life and total body clearance of acyclovir are dependent on renal function. A dosage adjustment is recommended for patients with reduced renal function (see DOSAGE AND ADMINISTRATION).

Geriatrics:

Acyclovir plasma concentrations are higher in geriatric patients compared with younger adults, in part due to age-related changes in renal function. Dosage reduction may be required in geriatric patients with underlying renal impairment (see PRECAUTIONS: Geriatric Use).

Pediatrics:

In general, the pharmacokinetics of acyclovir in pediatric patients is similar to that of adults. Mean half-life after oral doses of 300 mg/m2 and 600 mg/m2 in pediatric patients aged 7 months to 7 years was 2.6 hours (range 1.59 to 3.74 hours).

Drug Interactions:

Coadministration of probenecid with intravenous acyclovir has been shown to increase the mean acyclovir half-life and the area under the concentration-time curve. Urinary excretion and renal clearance were correspondingly reduced.

Clinical Trials:

Initial Genital Herpes: Double-blind, placebo-controlled studies have demonstrated that orally administered Acyclovir significantly reduced the duration of acute infection and duration of lesion healing. The duration of pain and new lesion formation was decreased in some patient groups.

Recurrent Genital Herpes: Double-blind, placebo-controlled studies in patients with frequent recurrences (6 or more episodes per year) have shown that orally administered Acyclovir given daily for 4 months to 10 years prevented or reduced the frequency and/or severity of recurrences in greater than 95% of patients.

In a study of patients who received Acyclovir 400 mg twice daily for 3 years, 45%, 52%, and 63% of patients remained free of recurrences in the first, second, and third years, respectively. Serial analyses of the 3-month recurrence rates for the patients showed that 71% to 87% were recurrence free in each quarter.

Herpes Zoster Infections: In a double-blind, placebo-controlled study of immunocompetent patients with localized cutaneous zoster infection, Acyclovir (800 mg 5 times daily for 10 days) shortened the times to lesion scabbing, healing, and complete cessation of pain, and reduced the duration of viral shedding and the duration of new lesion formation.

In a similar double-blind, placebo-controlled study, Acyclovir (800 mg 5 times daily for 7 days) shortened the times to complete lesion scabbing, healing, and cessation of pain; reduced the duration of new lesion formation; and reduced the prevalence of localized zoster-associated neurologic symptoms (paresthesia, dysesthesia, or hyperesthesia).

Treatment was begun within 72 hours of rash onset and was most effective if started within the first 48 hours.

Adults greater than 50 years of age showed greater benefit.

Chickenpox: Three randomized, double-blind, placebo-controlled trials were conducted in 993 pediatric patients aged 2 to 18 years with chickenpox. All patients were treated within 24 hours after the onset of rash. In 2 trials, Acyclovir was administered at 20 mg/kg 4 times daily (up to 3,200 mg per day) for 5 days. In the third trial, doses of 10, 15, or 20 mg/kg were administered 4 times daily for 5 to 7 days. Treatment with Acyclovir shortened the time to 50% healing; reduced the maximum number of lesions; reduced the median number of vesicles; decreased the median number of residual lesions on day 28; and decreased the proportion of patients with fever, anorexia, and lethargy by day 2. Treatment with Acyclovir did not affect varicella-zoster virus-specific humoral or cellular immune responses at 1 month or 1 year following treatment.

Adverse Reactions

Herpes Simplex: Short-Term Administration: The most frequent adverse events reported during clinical trials of treatment of genital herpes with Acyclovir 200 mg administered orally 5 times daily every 4 hours for 10 days were nausea and/or vomiting in 8 of 298 patient treatments (2.7%). Nausea and/or vomiting occurred in 2 of 287 (0.7%) patients who received placebo.

Long-Term Administration: The most frequent adverse events reported in a clinical trial for the prevention of recurrences with continuous administration of 400 mg (two 200-mg capsules) 2 times daily for 1 year in 586 patients treated with Acyclovir were nausea (4.8%) and diarrhea (2.4%). The 589 control patients receiving intermittent treatment of recurrences with Acyclovir for 1 year reported diarrhea (2.7%), nausea (2.4%), and headache (2.2%).

Herpes Zoster: The most frequent adverse event reported during 3 clinical trials of treatment of herpes zoster (shingles) with 800 mg of oral Acyclovir 5 times daily for 7 to 10 days in 323 patients was malaise (11.5%). The 323 placebo recipients reported malaise (11.1%).

Chickenpox: The most frequent adverse event reported during 3 clinical trials of treatment of chickenpox with oral Acyclovir at doses of 10 to 20 mg/kg 4 times daily for 5 to 7 days or 800 mg 4 times daily for 5 days in 495 patients was diarrhea (3.2%). The 498 patients receiving placebo reported diarrhea (2.2%).

Observed During Clinical Practice: In addition to adverse events reported from clinical trials, the following events have been identified during post-approval use of Acyclovir. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to either their seriousness, frequency of reporting, potential causal connection to Acyclovir, or a combination of these factors.

General: Anaphylaxis, angioedema, fever, headache, pain, peripheral edema.

Nervous: Aggressive behavior, agitation, ataxia, coma, confusion, decreased consciousness, delirium, dizziness, dysarthria, encephalopathy, hallucinations, paresthesia, psychosis, seizure, somnolence, tremors. These symptoms may be marked, particularly in older adults or in patients with renal impairment (see PRECAUTIONS).

Digestive: Diarrhea, gastrointestinal distress, nausea.

Hematologic and Lymphatic: Anemia, leukocytoclastic vasculitis, leukopenia, lymphadenopathy, thrombocytopenia.

Hepatobiliary Tract and Pancreas: Elevated liver function tests, hepatitis, hyperbilirubinemia, jaundice.

Musculoskeletal: Myalgia.

Skin: Alopecia, erythema multiforme, photosensitive rash, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria.

Special Senses: Visual abnormalities.

Urogenital: Renal failure, renal pain (may be associated with renal failure), elevated blood urea nitrogen, elevated creatinine, hematuria (see WARNINGS).

Acyclovir Oral Suspension Dosage and Administration

Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days.

Genital Herpes: Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.

Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.

The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with Acyclovir.

Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.

Treatment of Chickenpox: Children (2 years of age and older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.

Adults and Children over 40 kg: 800 mg 4 times daily for 5 days.

Intravenous Acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.

When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.

Patients With Acute or Chronic Renal Impairment: In patients with renal impairment, the dose of Acyclovir Capsules, Tablets, or Suspension should be modified as shown in Table 3.

Table 3. Dosage Modification for Renal Impairment
Normal Dosage
Regimen
 Creatinine 
 Clearance 
 (mL/min/1.73 m2) 
Adjusted Dosage Regimen
Dose
(mg)
Dosing Interval
 200 mg every 4 hours  >10 200  every 4 hours, 5x daily 
0-10 200  every 12 hours 
 400 mg every 12 hours  >10 400  every 12 hours 
0-10 200  every 12 hours 
 800 mg every 4 hours  >25 800  every 4 hours, 5x daily 
10-25 800  every 8 hours 
0-10 800  every 12 hours 

Hemodialysis: For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.

Peritoneal Dialysis: No supplemental dose appears to be necessary after adjustment of the dosing interval.

Bioequivalence of Dosage Forms: Acyclovir Suspension was shown to be bioequivalent to Acyclovir Capsules (n = 20) and 1 Acyclovir 800-mg tablet was shown to be bioequivalent to 4 Acyclovir 200-mg capsules (n = 24).

Highlights for acyclovir

Acyclovir is used to treat viral infections. These include varicella-zoster (shingles), genital herpes, and chickenpox.

Acyclovir is available as a tablet, capsule, suspension, and buccal tablet you take by mouth. (Buccal means you place the tablet between your gums and cheek, where it dissolves.) It also comes in a cream and ointment you apply to your skin. It’s also available as an intravenous (IV) drug, which is only given by a healthcare provider.

The oral suspension is available as the brand-name drug Zovirax. It’s also available as a generic drug.

The more common side effects of this drug include nausea, vomiting, diarrhea, headache, and weakness.

In some cases, acyclovir can cause serious side effects. These include kidney failure and dangerously low levels of red blood cells and platelets.

IMPORTANT INFORMATION
  • Kidney failure See Details

  • Low red blood cells and platelets See Details

  • Sexual contact See Details

What is acyclovir?

Acyclovir is a prescription drug. It’s available as an oral tablet, oral capsule, oral suspension, buccal tablet (a tablet you place between your gums and cheek to dissolve), topical cream, and topical ointment. It’s also available as an intravenous drug, which is only given by a healthcare provider.

The oral suspension is available as the brand-name drug Zovirax. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name version.

This drug may be used as part of a combination therapy. This means you may need to take it with other medications.

Why it's used

Acyclovir is used to treat viral infections. These include varicella-zoster (shingles), genital herpes, and chickenpox.

This drug doesn’t cure herpes infections. The herpes virus can stay in your body for a long time and cause symptoms again later.

How it works

Acyclovir belongs to a class of drugs called antivirals. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Acyclovir works by lowering the ability of the herpes virus to multiply in your body. This treats the symptoms of your infection.

More Details

How to Take acyclovir (Dosage)

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Shingles, genital herpes, or chickenpox

Generic: acyclovir

Form: Oral suspension Strengths: 200 mg/5 mL

Brand: Zovirax

Form: Oral suspension Strengths: 200 mg/5 mL Adult dosage (ages 18–64 years)
  • Shingles: 800 mg taken every 4 hours, five times per day for 7–10 days
  • Genital herpes:
    • Initial treatment: 200 mg taken every 4 hours, five times per day for 10 days
    • Prevention of recurrent herpes: Take 400 mg twice per day, every day for up to 12 months. Your doctor will decide how long you should take this drug to avoid a flare-up of the infection.
    • Reinfection (flare-up of the infection): Take 200 mg every 4 hours, five times per day for 5 days. You should take this drug as soon as the first signs of a flare-up appear.
  • Chickenpox: Take 800 mg four times per day for 5 days. Start this drug as soon as your first symptom of chickenpox appears. It isn’t known if this drug is effective if you start it more than 24 hours after the first sign of chickenpox.
Child dosage (ages 2–17 years)
  • Children who weigh 40 kg (88 lbs.) or less: 20 mg/kg of body weight, given four times per day for 5 days
  • Children who weigh more than 40 kg: 800 mg four times per day for 5 days

Start this drug as soon as the first symptom of chickenpox appears. It isn’t known if this drug is effective if you start it more than 24 hours after the first sign of chickenpox.

Child dosage (ages 0–1 years)

It hasn’t been confirmed that acyclovir is safe and effective for children younger than 2 years.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This increases your risk of side effects.

Your doctor may start you on a lowered dose or a different medication schedule. This can help keep levels of this drug from building up too much in your body.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you. Important considerations for taking this drug

You can take acyclovir with or without food

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Take this drug at the time(s) recommended by your doctor

Do not cut or crush this medication

Store this drug carefully

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A prescription for this medication is refillable

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Travel

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Clinical monitoring

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Your diet

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Sun sensitivity

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Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead.

Insurance

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Are there any alternatives?

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