Zovirax Drug Information

ZOVIRAX Cream is a herpes simplex virus (HSV) deoxynucleoside analogue DNA polymerase inhibitor indicated for the treatment of recurrent herpes labialis (cold sores) in immunocompetent adults and adolescents 12 years of age and older.

• ZOVIRAX Cream should be applied 5 times per day for 4 days. Therapy should be initiated as early as possible following the onset of signs or symptoms of herpes labialis, i.e. during the prodrome or when lesions appear. For adolescents 12 years of age and older, the dosage is the same as in adults.
• Apply 5 times a day for 4 days.
• Administer immediately following the onset of cold sore lesions.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug, and may not reflect the rates observed in clinical practice. In five double-blind, placebo-controlled trials, 1124 patients were treated with ZOVIRAX Cream and 1161 with placebo (vehicle) cream. Local application site reactions were reported by 5% of patients receiving ZOVIRAX Cream and 4% of patients receiving placebo.

The most common adverse reactions at the site of topical application were dry lips, desquamation, dryness of skin, cracked lips, burning skin, pruritus, flakiness of skin, and stinging on skin; each adverse reaction occurred in less than 1% of patients receiving ZOVIRAX Cream and placebo. Three patients on ZOVIRAX Cream and one patient on placebo discontinued treatment due to an adverse event. An additional study, enrolling 22 healthy adults, was conducted to evaluate the dermal tolerance of ZOVIRAX Cream compared with vehicle using single occluded and semi-occluded patch testing methodology.

Both ZOVIRAX Cream and placebo showed a high and cumulative irritation potential. Another study, enrolling 251 healthy adults, was conducted to evaluate the contact sensitization potential of ZOVIRAX Cream using repeat insult patch testing methodology. Of 202 evaluable subjects, possible cutaneous sensitization reactions were observed in the same 4 (2%) subjects with both ZOVIRAX Cream and placebo, and these reactions to both ZOVIRAX Cream and placebo were confirmed in 3 subjects upon rechallenge.

The sensitizing ingredient(s) has not been identified. The safety profile in patients 12 to 17 years of age was similar to that observed in adults.

Postmarketing Experience

In addition to adverse events reported from clinical trials, the following events have been identified during postapproval use of acyclovir cream. 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 a combination of their seriousness, frequency of reporting, or potential causal connection to acyclovir cream.

General: Angioedema, anaphylaxis. Skin: Contact dermatitis, eczema.

• Clinical experience has identified no interactions resulting from topical or systemic administration of other drugs concomitantly with ZOVIRAX Cream. Due to minimal systemic absorption of ZOVIRAX Cream, systemic drug interactions are unlikely.

Pregnancy Risk Summary Acyclovir is minimally absorbed systemically following topical route of administration, and maternal use is not expected to result in fetal exposure to the ZOVIRAX Cream. Experience with topical acyclovir use in pregnant women over several decades, based on published literature including observational studies, has not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Animal reproduction studies with systemic exposure of acyclovir have been conducted.

Refer to acyclovir prescribing information for additional details. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes.

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is respectively.

Pediatric Use An open-label, uncontrolled trial with ZOVIRAX Cream was conducted in 113 patients aged 12 to 17 years with recurrent herpes labialis. In this trial, therapy was applied using the same dosing regimen as in adults and subjects were followed for adverse events. The safety profile was similar to that observed in adults.

Safety and effectiveness in pediatric patients less than 12 years of age have not been established.

• ZOVIRAX Cream is contraindicated in patients with known hypersensitivity to acyclovir, valacyclovir, or any component of the formulation.

Overdosage by topical application of ZOVIRAX Cream is unlikely because of minimal systemic exposure. There is no information available for overdose.