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Acyclovir (ointment) is an antiviral that is FDA approved for the treatment of genital herpes and in limited non-life threatening mucocutaneous herpes simplex virus infections in immunocompromised patients. Common adverse reactions include pain, edema, pruritis, and rash.
Adult Indications and Dosage
FDA-Labeled Indications and Dosage (Adult)
- Acyclovir ointment 5% is indicated in the management of initial genital herpes and in limited non-life threatening mucocutaneous herpes simplex virus infections in immunocompromised patients.
- Apply sufficient quantity to adequately cover all lesions every 3 hours, 6 times per day for 7 days. The dose size per application will vary depending upon the total lesion area but should approximate a one-half inch ribbon of ointment per 4 square inches of surface area. A finger cot or rubber glove should be used when applying acyclovir ointment to prevent autoinoculation of other body sites and transmission of infection to other persons. Therapy should be initiated as early as possible following onset of signs and symptoms.
Off-Label Use and Dosage (Adult)
There is limited information regarding Off-Label Guideline-Supported Use of Acyclovir (ointment) in adult patients.
There is limited information regarding Off-Label Non–Guideline-Supported Use of Acyclovir (ointment) in adult patients.
Pediatric Indications and Dosage
FDA-Labeled Indications and Dosage (Pediatric)
There is limited information regarding FDA-Labeled Use of Acyclovir (ointment) in pediatric patients.
Off-Label Use and Dosage (Pediatric)
There is limited information regarding Off-Label Guideline-Supported Use of Acyclovir (ointment) in pediatric patients.
There is limited information regarding Off-Label Non–Guideline-Supported Use of Acyclovir (ointment) in pediatric patients.
- Acyclovir ointment 5% is contraindicated in patients who develop hypersensitivity to the components of the formulation.
- Acyclovir ointment 5% is intended for cutaneous use only and should not be used in the eye.
Clinical Trials Experience
- In the controlled clinical trials, mild pain (including transient burning and stinging) was reported by about 30% of patients in both the active and placebo arms; treatment was discontinued in two of these patients. Local pruritus occurred in 4% of these patients. In all studies, there was no significant difference between the drug and placebo group in the rate or type of reported adverse reactions nor were there any differences in abnormal clinical laboratory findings.
Observed During Clinical Practice
- Based on clinical practice experience in patients treated with acyclovir ointment in the U.S., spontaneously reported adverse events are uncommon. Data are insufficient to support an estimate of their incidence or to establish causation. These events may also occur as part of the underlying disease process. Voluntary reports of adverse events that have been received since market introduction include:
- General: Edema and/or pain at the application site.
- Skin: Pruritus, rash.
There is limited information regarding Postmarketing Experience of Acyclovir (ointment) in the drug label.
- Clinical experience has identified no interactions resulting from topical or systemic administration of other drugs concomitantly with acyclovir ointment 5%.
Use in Specific Populations
- Acyclovir was not teratogenic in the mouse, rabbit or rat at exposures greatly in excess of human exposure. There are no adequate and well controlled studies of systemic acyclovir in pregnant women. A prospective epidemiologic registry of acyclovir use during pregnancy was established in 1984 and completed in April 1999.
- There were 749 pregnancies followed in women exposed to systemic acyclovir during the first trimester of pregnancy resulting in 756 outcomes. The occurrence rate of birth defects approximates that found in the general population. However, the small size of the registry is insufficient to evaluate the risk for less common defects or to permit reliable or definitive conclusions regarding the safety of acyclovir in pregnant women and their developing fetuses. Systemic acyclovir should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
- Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Acyclovir (ointment) in women who are pregnant.
Labor and Delivery
There is no FDA guidance on use of Acyclovir (ointment) during labor and delivery.
- It is not known whether topically applied acyclovir is excreted in breast milk. Systemic exposure following topical administration is minimal. After oral administration of acyclovir, acyclovir concentrations have been documented in breast milk in two women and ranged from 0.6 to 4.1 times the corresponding plasma levels. These concentrations would potentially expose the nursing infant to a dose of acyclovir up to 0.3 mg/kg per day. Nursing mothers who have active herpetic lesions near or on the breast should avoid nursing.
There is no FDA guidance on the use of Acyclovir (ointment) with respect to pediatric patients.
- Clinical studies of acyclovir ointment did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. Systemic absorption of acyclovir after topical administration is minimal.
There is no FDA guidance on the use of Acyclovir (ointment) with respect to specific gender populations.
There is no FDA guidance on the use of Acyclovir (ointment) with respect to specific racial populations.
There is no FDA guidance on the use of Acyclovir (ointment) in patients with renal impairment.
There is no FDA guidance on the use of Acyclovir (ointment) in patients with hepatic impairment.
Females of Reproductive Potential and Males
There is no FDA guidance on the use of Acyclovir (ointment) in women of reproductive potentials and males.
There is no FDA guidance one the use of Acyclovir (ointment) in patients who are immunocompromised.
Administration and Monitoring
There is limited information regarding Monitoring of Acyclovir (ointment) in the drug label.
There is limited information regarding IV Compatibility of Acyclovir (ointment) in the drug label.
Overdosage by topical application of acyclovir ointment 5% is unlikely because of limited transcutaneous absorption
Mechanism of Action
- Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV- 2), and varicella-zoster virus (VZV).
- The inhibitory activity of acyclovir is highly selective due to its affinity for the enzyme thymidine kinase (TK) encoded by HSV and VZV. This viral enzyme converts acyclovir into acyclovir monophosphate, a nucleotide analogue. The monophosphate is further converted into diphosphate by cellular guanylate kinase and into triphosphate by a number of cellular enzymes. In vitro, acyclovir triphosphate stops replication of herpes viral DNA. This is accomplished in 3 ways: 1) competitive inhibition of viral DNA polymerase, 2) incorporation into and termination of the growing viral DNA chain, and 3) inactivation of the viral DNA polymerase. The greater antiviral activity of acyclovir against HSV compared to VZV is due to its more efficient phosphorylation by the viral TK.
- The quantitative relationship between the in vitro susceptibility of herpes viruses to antivirals and the clinical response to therapy has not been established in humans, and virus sensitivity testing has not been standardized. Sensitivity testing results, expressed as the concentration of drug required to inhibit by 50% the growth of virus in cell culture (IC50), vary greatly depending upon a number of factors. Using plaque-reduction assays, the IC50 against herpes simplex virus isolates ranges from 0.02 to 13.5 mcg/mL for HSV-1 and from 0.01 to 9.9 mcg/mL for HSV-2. The IC50 for acyclovir against most laboratory strains and clinical isolates of VZV ranges from 0.12 to 10.8 mcg/mL. Acyclovir also demonstrates activity against the Oka vaccine strain of VZV with a mean IC50 of 1.35 mcg/mL.
- Resistance of HSV and VZV to acyclovir can result from qualitative and quantitative changes in the viral TK and/or DNA polymerase. Clinical isolates of HSV and VZV with reduced susceptibility to acyclovir have been recovered from immunocompromised patients, especially with advanced HIV infection. While most of the acyclovir-resistant mutants isolated thus far from immunocompromised patients have been found to be TK-deficient mutants, other mutants involving the viral TK gene (TK partial and TK altered) and DNA polymerase have been isolated. TK-negative mutants may cause severe disease in infants and immunocompromised adults. The possibility of viral resistance to acyclovir should be considered in patients who show poor clinical response during therapy.
There is limited information regarding Acyclovir (ointment) Structure in the drug label.
There is limited information regarding Pharmacodynamics of Acyclovir (ointment) in the drug label.
- Two clinical pharmacology studies were performed with acyclovir ointment 5% in immunocompromised adults at risk of developing mucocutaneous herpes simplex virus infections or with localized varicella-zoster infections. These studies were designed to evaluate the dermal tolerance, systemic toxicity and percutaneous absorption of acyclovir.
- In one of these studies, which included 16 inpatients, the complete ointment or its vehicle were randomly administered in a dose of 1 cm strips (25 mg acyclovir) 4 times a day for 7 days to an intact skin surface area of 4.5 square inches. No local intolerance, systemic toxicity or contact dermatitis were observed. In addition, no drug was detected in blood and urine by radioimmunoassay (sensitivity, 0.01 mcg/mL).
- The other study included 11 patients with localized varicella-zoster infections. In this uncontrolled study, acyclovir was detected in the blood of nine patients and in the urine of all patients tested. Acyclovir levels in plasma ranged from < 0.01 to 0.28 mcg/mL in eight patients with normal renal function, and from < 0.01 to 0.78 mcg/mL in one patient with impaired renal function. Acyclovir excreted in the urine ranged from < 0.02% to 9.4% of the daily dose. Therefore, systemic absorption of acyclovir after topical application is minimal.
There is limited information regarding Nonclinical Toxicology of Acyclovir (ointment) in the drug label.
- In clinical trials of initial genital herpes infections, acyclovir ointment 5% has shown a decrease in healing time and, in some cases, a decrease in duration of viral shedding and duration of pain. In studies in immunocompromised patients mainly with herpes labialis, there was a decrease in duration of viral shedding and a slight decrease in duration of pain.
- In studies of recurrent genital herpes and of herpes labialis in non-immunocompromised patients, there was no evidence of clinical benefit; there was some decrease in duration of viral shedding.
- Each gram ofAcyclovir Ointment USP, 5% contains acyclovir USP, 50 mg in a polyethylene glycol base. Acyclovir Ointment USP, 5% is an opaque white to off-white ointment available as follows:
- carton of one 15 g tube
- carton of one 30 g tube
- Keep out of the reach of children.
- Store at 20° to 25°C (68° to 77°F)
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Patient Counseling Information
There is limited information regarding Patient Counseling Information of Acyclovir (ointment) in the drug label.
Precautions with Alcohol
- Alcohol-Acyclovir (ointment) interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.
Look-Alike Drug Names
There is limited information regarding Acyclovir (ointment) Look-Alike Drug Names in the drug label.
The contents of this FDA label are provided by the National Library of Medicine.
- "Zovirax (acyclovir) dosing, indications, interactions, adverse effects, and more". Medscape Reference. WebMD. Retrieved 5 February 2014.
- "ACYCLOVIR- acyclovir ointment".