Drug information of Acyclovir


Drug group:

Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus in the body. It will not cure herpes, but it can lessen the symptoms of the infection. Acyclovir is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox.

Mechanism of effect

Aciclovir triphosphate competitively inhibits viral DNA polymerase and competes with the natural deoxyguanosine triphosphate, for incorporation into viral DNA


Acyclovir is a synthetic purine nucleoside analogue with in vitro andin vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV).


The oral bioavailability is 10% to 20%, and decreases with increasing dose. Food does not affect the absorption of acyclovir. Metabolism: Hepatic. Primarily excreted unchanged by the kidneys via active tubular secretion. Half life: 2.5-3.3 hours

Drug indications

Herpes Zoster , Chickenpox , Genital Herpes


Usual Adult Dose for Herpes Zoster
Acute herpes zoster:
800 mg orally every 4 hours (5 times a day) for 7 to 10 days
Severe, immunocompromised host: 10 mg/kg IBW IV every 8 hours for 7 to 14 days
Therapy should be initiated within 72 hours after onset of rash, although, during clinical trials, acyclovir was most effective when initiated within the first 48 hours.
Usual Adult Dose for Varicella-Zoster
Immunocompetent host: 800 mg orally four times a day for 5 days
Immunocompromised host: 10 mg/kg IBW IV every 8 hours for 7 to 10 days or until no new lesions for 48 hours; after fever abates and if there is no proof of visceral involvement, the patient may be switched to 800 mg orally four times a day
Therapy should be initiated at the earliest sign of chickenpox, no later than 24 hours after onset of rash.
Usual Pediatric Dose for Herpes Simplex
Neonatal HSV infection:
Less than 3 months: 10 to 20 mg/kg or 500 mg/m2 IV every 8 hours for 10 to 21 days Some clinicians recommend 10 mg/kg every 12 hours for premature neonates.


Acyclovir capsules are intended for oral ingestion only. Renal failure, in some cases resulting in death, has been observed with acyclovir therapy . Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.

Points of recommendation

1-Patients should be advised to initiate treatment as soon as possible after a diagnosis of herpes zoster.
2-Patients should be informed that acyclovir is not a cure for genital herpes. There are no data evaluating whether acyclovir will prevent transmission of infection to others.
3- If medical management of a genital herpes recurrence is indicated, patients should be advised to initiate therapy at the first sign or symptom of an episode.
4- Chickenpox in otherwise healthy children is usually a self-limited disease of mild to moderate severity. Adolescents and adults tend to have more severe disease. Treatment was initiated within 24 hours of the typical chickenpox rash in the controlled studies, and there is no information regarding the effects of treatment begun later in the disease course.

Pregnancy level


Related drugs

Valacyclovir , Docosanol

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