Acyclovir is available under different brand names and Zovirax is a common brand name for this drug. Acyclovir belongs to the antiviral class of drugs. The drug is FDA (Food and Drug Administration) approved prescription drug for the treatment of genital herpes, cold sores and certain other similar kind of infections. Acyclovir can be used as a topical, oral and injectable treatment depending on the condition.
What Is Acyclovir and How It Works Against Herpes Infections?
Acyclovir is the generic name of this drug and is sold under various brand names. Acyclovir is an effective antiviral drug mostly prescribed by doctors for the treatment of a variety of herpes infections such as cold sores, genital herpes infections, shingles (herpes zoster infections), chicken pox and encephalitis. It is available in the form of tablets, oral suspension and capsules.
Genital herpes infection is a sexually transmitted disease that any sexually active person can acquire and transmit to his/her partners during intercourse. Genital herpes is caused by herpes simplex type 1 and herpes simplex type 2.
Many people suffering from genital herpes have no idea that they are infected. The symptoms of infection usually appear after some days or weeks after the exposure. Common symptoms of this infection include flu-like symptoms (fever, swollen glands or body aches), blisters (that pop up and cause painful sores) blisters, rash or sores in the genital area with or without pain, tingling and itching.
Chicken pox and shingles are common skin diseases. These are skin infections and both are caused by herpes viruses. Shingles and chickenpox are caused by herpes virus but that is not the same virus that causes genital herpes and cold sores. People who get infected with chicken pox or shingles experience symptoms including rash usually accompanied by pain that is treatable with Acyclovir.
There is no complete cure for herpes however Acyclovir treatment helps ease and decrease the symptoms of infections. Acyclovir may also help ease pain associated with a genital herpes outbreak after the sores heal. Aciclovir tablets are indicated for acute treatment of shingles, initial episodes of genital herpes and management of recurrent episodes of genital herpes infections.
Acyclovir 400 mg Tablets
Acyclovir medication is used to treat a variety of viral infections. Acyclovir is a synthetic purine nucleoside analogue that works against herpes viruses. Acyclovir tablets are formulated for oral administration. Acyclovir tablets are available as Acyclovir 200 mg, 400 mg and 800 mg tablets. It is a typical medication for preventing recurrent herpes.
Each Acyclovir 400 mg tablet contains 400 mg of Acyclovir and inactive ingredients croscarmellose sodium, magnesium stearate, colloidal silicon dioxide and microcrystalline cellulose. Similarly, each Acyclovir 800 mg tablet contains 800 mg of Acyclovir and the active ingredients croscarmellose sodium, colloidal silicon dioxide, microcrystalline cellulose and magnesium stearate.
Acyclovir triphosphate meddles with the viral DNA polymerase and restricts the replication of viral DNA with resultant chain termination resulting its incorporation into the viarl DNA.
400 Mg Acyclovir Dosage for Cold Sore Treatment and Other Herpes Infections?
Typical Adult Dosage for Herpes Simplex Mucocutaneous or Immunocompetent Patients
The oral dosage for the first episode of genital herpes treatment is 200 mg five times a day for 10 days at an interval of four hours or 400 mg three times a day for 5-10 days.
For severe infections or complications requiring hospitalization, the recommended dosage is Acyclovir 5mg/kg IV every eight hours for 5 days or 5 to 10 mg/kg IV every eight hours for 2-7 days. The duration of treatment can be continued until clinical improvement is found accompanied by oral antiviral therapy for at least 10 days.
Effective treatment for the infection needs therapy commencement within 1 day of lesion onset or during the prodrome preceding an episode or recurrence. The oral dosage is 200 mg five times a day for 5 days at an interval of four hours as per the manufacturer’s recommendation. The oral dosage as per CDC recommendations is 400 mg three times a day for 5 days or 800 mg two times a day for 5 days.
Typical Adult dosage for Concomitant HIV infection:
The usual oral dosage for the treatment of the first episode of genital herpes is 400 mg three times a day for 5-10 days.
For severe disease, the recommended dosage is 5 mg/kg IV every eight hours post the regression of lesions. The treatment may be required until the lesions get healed completely.
Effective treatment needs therapy initiation within one day of the onset of the lesion or during the prodrome preceding an episode or recurrence. The oral dosage is 400 mg three times a day for 5-14 days.
General Adult Dosage for Herpes Simplex Encephalitis
The recommended dosage per CDC guidelines is 10 mg/kg intravenously every eight hours for 10 to 21 days.
Usual Adult Dosage for Herpes Zoster (Shingles)
The typical oral dosage for herpes zoster infection is Acyclovir 800 mg five times a day for 7-10 days. Make sure to maintain a four-hour gap between each dose. For immunocompromised hosts, the dosage is 10 mg/kg IV every eight hours for 7 days.
The oral dosage for concomitant HIV infection (localized dermatomal) is 800 mg five times a day for 7-10 days (oral Famciclovir and Valacyclovir are preferred as alternative therapy). In case of extensive cutaneous lesion or visceral involvement, the recommended dosage is 10 to 15 mg/kg intravenously every eight hours until clinical improvement is observed then the patient can switch to oral treatment.
Begin with the treatment as soon as possible after the diagnosis of shingles infection. The parenteral dosing schedule depends on the ideal body weight of the patient. Acyclovir oral therapy should be considered alternative therapy in case of acute localized dermatomal shingles infection in HIV-infected patients. Intravenous dosing is preferred with extensive cutaneous lesions or visceral involvement.
General Adult Dosage for Varicella Zoster (Chickenpox)
Immunocompetent Patients
The recommended oral dosage is Acyclovir 800 mg four times a day for 5 days.
Immunocompromised Patients
The recommended dosage is Acyclovir 10 mg/kg intravenously every eight hours for 7 days.
HIV-infected Patients
The uncomplicated course oral dosage is 800 mg five times a day for 5-7 days. The complicated or severe course dosage is 10-15 mg/kg intravenously every eight hours for 7-10 days. Patients can switch to oral treatment after defervescence in case no visceral involvement is found. Initiate the treatment as soon as possible after you notice the earliest sign of chickenpox.
Typical Adult Dosage for Herpes Simplex Labialis (Cold Sores)
Immunocompetent Host
For herpes simplex labialis buccal tablets are prescribed. Place 1 buccal tablet (50 mg) as a single dose on the upper gum area. It is best to place the tablet within an hour after the onset of prodromal symptoms and before any signs of lesions appear.
Concomitant HIV Infection
The oral dosage is 400 mg three times a day for 5-10 days.
Typical Dosage for Herpes Simplex Suppression
The dosage for daily suppressive therapy for recurrent disease is 400 mg orally two times a day. Alternative oral therapies from 200 mg three to five times a day have been used.
Concomitant HIV Infection
The recommended oral dosage is Acyclovir 400 mg to 800 mg two to three times a day.
Suppressive therapy reduces the frequency of recurrence of infection by 70-80% in patients who experience frequent recurrences. Recurrences of infection have been shown to reduce over time thus continued therapy should be reevaluated annually or as suggested by your doctor.
Typical Adult Dosage for Herpes Zoster Prophylaxis
The guideline dosing for HIV-infected adults in case of post-exposure prophylaxis is 800 mg orally five times a day for 5-7 days. Treatment should be beginning 7-10 days after exposure.
Typical Adult Dosage for Varicella Zoster Prophylaxis
The guideline dosing for HIV-infected adults post-exposure prophylaxis is 800 mg orally five times a day for 5-7 days which needs to be begun 7-10 days post-exposure.
What is Acyclovir 400 mg Dosage for Paediatric Patients?
Typical Paediatric Dosage for Herpes Simplex Congenital
Neonatal Herpes
As per the manufacturer’s recommendation, the dosage for children up to three months of age is 10 mg/kg intravenously every eight hours for 10 days. As per CDC recommendation, the dosage for children up to three months of age is 20 mg/kg intravenously every 8 hours.
If the disease is limited to skin and mucous membranes, the duration of treatment is 14 days and if the disease is disseminated involving CNS the duration of therapy is 21 days. Oral suppressive therapy of 300 mg/m2 three times a day for six months should be followed.
Neonates who are born to Herpes Simplex Virus infected women near term need to be treated because of the higher risk of infection. Infants infected with HSV during birth need to be followed by a paediatric infectious-disease specialist.
For neonatal HSV infection involving CNS, make sure to confirm that the virus is absent from the cerebrospinal fluid before stopping the treatment. CSF HSV DNA PCR must be performed on the 19th and 21st day and repeated if required.
General Pediatric Dosage for Herpes Simplex- Mucocutaneous or Immunocompetent Host
Safety and efficacy of Acyclovir oral formulations in pediatric patients below 2 years of age has not been established.
Dosage for First Episode of Genital Herpes Infections
The recommended dosage for pediatric patients less than 12 years is 40 to 80 mg/kg per day orally three to four times every day for 5-10 days. The maximum dosage is 1000 mg/kg. For children aged 12 years or older the oral dosage is 200 mg every four hours five times every day or 400 mg three times every day for 7-10 days.
In case of complications or severe disease requiring hospitalization the dosage for children less than 12 years of age is 10 mg/kg IV every eight hours for 7 days. The dosage for children 12 years or older is 5 mg/kg IV every eight hours for 7 days.
In case of recurrence of genital herpes infection, the oral dosage for children less than 12 years of age is 20 to 25 mg/kg twice a day. The dose should not exceed 400 mg. The oral dosage for children aged 12 years or older is 200 mg five times a day for 5 days or 800 mg twice a day for 5 days.
Typical Pediatric Dosage for Herpes Simplex Encephalitis
The recommended dosage for paediatric patients aged 3 months to 12 years is 10 to 20 mg/kg intravenously every 8 hours. For children aged 12 years or older, the dosage is 10 to 20 mg/kg IV every 8 hours for 10 to 21 days depending on the condition and response to the treatment.
Usual Paediatric Dosage for Herpes Simplex-Mucocutaneous/ Immunocompromised Patients
For children below 12 years the dosage is 10mg/kg intravenously every eight hours for 7 days and children aged 12 years or above the dosage is 5 mg/kg intravenously every eight hours for 7 days.
Guideline Dosing for Concomitant HIV Infection
The oral dosage for mild symptomatic Gingivostomatitis is 20 mg/kg four times a day for 7-10 days. The maximum recommended dosage is 400 mg.
The dosage for moderate to severe gingivostomatitis is 5 to 10 mg/kg intravenously 3 times a day. The doctor may recommend switching to oral therapy after lesions begin to regress and treat until lesions heal completely.
Typical Paediatric Dosage for Herpes Zoster (Shingle)
Immunocompetent Host
Parenteral: For children below one year of age the dosage is 10 mg/kg intravenously every eight hours 7-10 days. For children aged one year or older, the dosage is 500 mg/kg intravenously every eight hours for 7-10 days.
The dosage for immunocompromised hosts is 10 mg/kg intravenously every eight hours for 7-10 days.
HIV-exposed and HIV-infected Children
The recommended oral dosage for uncomplicated zoster is 20 mg/kg four times a day for 7-10 days and the maximum dosage is 800 mg.
The dosage for severe immunosuppression, trigeminal or sacral nerve involvement, and extensive multi-dermatomal or disseminated zoster is 10 mg/kg intravenously every eight hours until cutaneous lesions and visceral disease resolve completely. Then patient may switch to oral treatment to complete a 10-14-day course.
HIV-infected Adolescents
In the case of localized dermatomal, the dosage is 800 mg orally five times a day for 7-10 days. In case of cutaneous lesion or visceral involvement the dosage is 10 to 15 mg/kg intravenously every eight hours until you notice visible clinical improvement and then switch to oral therapy.
Acyclovir oral medication is the drug of choice for the treatment of herpes zoster in HIV-infected kids, it should be given to infected kids for 7-10 days. Longer durations of treatment can be considered if lesions are resolving slowly.
Typical Paediatric Dosage for Varicella-Zoster Virus
Immunocompetent patients
For children aged two years or older (less than 40 kg body weight), the oral dosage is 20 mg/kg four times a day for 5 days. For children two years or older (over 40 kg body weight) 800 mg orally four times a day for 5 days. Maximum dosage should be 800 mg (single) and 3200 mg/day.
Immunocompromised Patients
For patients below one year of age 10 mg/kg intravenously three times a day for 7-10 days. For children aged one year or older 500 mg/m2 intravenously three times a day for 7-10 days.
HIV-infected Adolescents
Therapy should be started as you notice the earliest signs of chickenpox. The dosage for uncomplicated courses is 800 mg orally five times a day for 5-7 days.
The dosage for severe or complicated courses is 10 to 15 mg/kg intravenously every eight hours for 7-10 days. The patient may switch to oral treatment after defervescence if no visceral involvement is there.
Typical Pediatric Dosage for Herpes Simplex Labialis (Cold Sores)
Concomitant HIV infection
The recommended oral dose is 20 mg/kg four times a day for 5 days. For adolescents, the oral dosage is 400 mg three times a day for 5-10 days.
The safety and effectiveness of Acyclovir buccal tablets have not been evaluated for paediatric patients. Using buccal tablets in younger children may cause the risk of choking.
Typical Paediatric Dosage for Herpes Zoster Prophylaxis
HIV-infected Children or Adolescents
The recommended dosage post-exposure prophylaxis in HIV-infected children or adolescents is 20 mg/kg orally four times a day for 7-10 days after exposure.
Usual Pediatric Dosage for Varicella Zoster Prophylaxis
HIV-infected Children or Adolescents
The usual dosage post-exposure prophylaxis in HIV-infected children or adolescents is 20 mg/kg orally four times a day for 7-10 days.
Dosing Modifications
Dose adjustments depending on renal clearance (ml min 1.73) and normal dosing schedule
200 mg every 4 hours:
0-10 mL/min.1.73 m²: 200 mg every 12 hours
Over 10 mL/min/1.73 m²: 200 mg every four hours five times every day.
400 mg every 12 hours:
0-10 mL/min/1.73 m²: 200 mg every 12 hours
Over 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
Over 25 mL/min/1.73 m²: 800 mg every 4 hours 5 times every day.
Dose adjustment based on the dosage form
Elderly patients with renal impairment require dose reduction or modifications in Aciclovir dosages and mostly elderly patients are more likely to have reduced renal function. Thus elderly patients as well as patients with reduced renal function or impaired renal function should be closely monitored during the treatment.
Renal Impairment Treatment (IV Therapy)
- CrCl 25-50 mL/min/1.73 m²: Given every 12 hours
- CrCl 10-25 mL/min/1.73 m²: Given every 24 hours
- CrCl less than 10 mL/min/1.73 m²: Give 50% of the suggested dose every 24 hours
Renal impairment (Oral)
- The typical dosage is 200 mg every 4 hours or 400 mg every 12 hours and CrCl below 10 mL/min/1.73 m²: Reduce to 200 mg every 12 hours.
