Zovirax – What It Is and How It Works 5/5 (1)

Acyclovir is sold under the brand name Zovirax. It is an antiviral drug active against herpes viruses. Zovirax Ointment 5% is a formulation for topical administration. Each gram of Zovirax Ointment 5% contains 50 mg of acyclovir in a polyethylene glycol base

What is Zovirax?

Zovirax (acyclovir) Ointment 5% is the first effective drug for genital herpes, a sexually-transmitted disease that afflicts up to 20 million people in the United States. It is a breakthrough antiviral drug discovered and developed by Burroughs Welcome Co. It is a new chemical entity and major therapeutic advance that was classified as a “fast track” drug for FDA review.

Why is Zovirax so significant?

Zovirax represents a new era in antiviral therapy. Its unique mechanism of action allows it to attack the virus selectively with little likelihood of toxicity to the patient. It could-be a prototype for other antivirals. Zovirax will be the first drug safe enough to allow investigations of its potential use against a wide variety of infections caused by the herpes virus family.

What is the therapeutic profile?

Zovirax Ointment is indicated in the management of patients with initial herpes genitals. It is also indicated for immunocompromised patients with limited nonlife-threatening cutaneous HSV infections. In double-blind placebo-controlled clinical trials, Zovirax Ointment but shown decreases in healing time, some decrease in duration of viral shedding, and duration of pain in these patients.

Is Zovirax effective in treating recurrent episodes of herpes?

Zovirax Ointment’s indication in these conditions is limited to a decrease in viral shedding. Based on studies performed and analyzed to date, no claim is made for any effect beyond this in these conditions. The clinical significance of viral shedding has not yet been clearly defined.

Studies have shown that Zovirax hastens the elimination of HSV from established lesions of initial and recurrent genital and labial infections in both normal and immunocompromised patients. This decrease in viral shedding proves the antiviral effect of Zovirax.

In addition to the observed antiviral effects, clinical benefits were observed in normal patients with the first (“initial”) episode of herpes genitals, and in immunocompromised patients with either initial or recurrent herpes genitalis and herpes labialis. However, in normal patients with established lesions of recurrent herpes genitalis and labialis, infections are characteristically of shorter duration and less severe. Therefore, the use of the topical ointment relatively late in these patients did not show a significant reduction in clinical signs or symptoms, even though an antiviral effect was demonstrated.

Whether these observations would be applicable to all normal patients with recurrent herpes infections, or reflect only conditions under that particular study design, is unknown. Data from additional studies in recurrent herpes genitalis with therapy initiated earlier may provide evidence whether this topical formulation will offer clinical benefit for these indications.

What is the mechanism of action?

Zovirax normally exists in its inactive form. It is preferentially taken up and selectively converted to its active form by the herpes virus-infected cell. This conversion does not occur to any significant degree in normal cells.

Once Zovirax is activated in the HSV-infected cell, it interferes with the synthesis of viral DNA essential for new virus particles. Thus, Zovirax inhibits viral replication. Simplistically, the virus commits suicide by activating and converting Zovirax to a form that is toxic to the virus itself. Because of this unique mechanism of action, Zovirax is an extremely well-tolerated product.

How can Zovirax be so effective and yet so well tolerated?

Zovirax is virtually inactive in normal cells. It becomes biologically active to a significant degree only in virus-infected cells, because it needs the presence of herpes enzymes to work. The herpes virus enzyme, thymidine kinase, initiates the conversion of Zovirax to a form that blocks the replication of the virus. This means that Zovirax is able to fight the virus with little damage to normal body cells, and there is little likelihood of toxicity for patients.

Is Zovirax a “cure” for herpes infections?

No. Zovirax has no effect on latent virus in the nerve ganglion. It stops the production of the virus once the virus starts to replicate.

What is the side effect profile?

A. In all studies, there was no significant difference between the drug and the placebo in the rate or type of reported adverse reactions nor were there any differences in abnormal clinical laboratory findings. Because ulcerated lesions are characteristically tender and sensitive to any contact or manipulation, patients may experience discomfort upon application of the ointment.

In controlled clinical trials, mild pain (including transient burning and stinging) was reported by Drs. Corey and Holmes to be “more frequent with first episodes of genital herpes (29%) than with recurrent episodes (6%), and is more frequent in women (36%) than in men (8%). Topical acyclovir in polyethylene glycol in not approved for intravaginal use; the polyethylene glycol base may cause vaginal erythema.” Less frequent reactions included pruritus, rash and vulvitis.

Does Zovirax interact with other drugs?

Clinical experience has identified no interactions resulting from the concomitant use of topical Zovirax with M1 other drugs.

What about contraindications, warnings or precautions?

Zovirax ointment 5% is contraindicated for those patients who develop hypersensitivity or chemical intolerance to the components of the formulation. It is intended for cutaneous use only and should not be used in the eye.

The recommended dosage, frequency of applications, and length of treatment should not be exceeded. There exists no data that demonstrate that the use of Zovirax Ointment will either prevent transmission of infection to other persons or prevent recurrent infections when applied in the absence of signs and symptoms.

Acyclovir is classified in Pregnancy Category C. Although there are no adequate and well-controlled studies in pregnant women, acyclovir should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

What is the recommended dosage?

Zovirax ointment 5% should be applied in sufficient quantity to adequately cover all lesions every three hours, six times per day. Drs. Corey and Holmes in the Annals of Internal Medicine recommend “an application of all external genital lesions four to six times daily for 7 to 14 days, or until all lesions have crusted.

Herpes & Sexually Transmitted Diseases

Although the duration of therapy used in clinical trials and now recommended by the manufacturer is 7 days, a longer course of therapy might be more effective for some patients to prevent delayed new lesion formation. We do not recommend routine use of [Zovirax] in patients with recurrent genital herpes. However, early application of ointment in those episodes of recurrent disease involving large lesion areas (50 to 150 mm’) may have slight benefit to male patients.” A finger cot or rubber glove should be used when applying Zovirax to prevent autoinoculation of other body sites and transmission of infection to other persons.

How is the drug supplied and how much will it cost?

Zovirax Ointment 5% is supplied in 15g tubes with each gram containing 50mg of acyclovir in a polyethylene glycol base. It should be stored at 15°C to 25°C (59°F to 78°F) in a dry place. It will cost the patient upon prescription approximately $18-$21.

How many episodes of herpes will a single tube of Zovirax treat?

The amount of Zovirax in a 15g tube should be more than adequate to treat a case of initial herpes genitalis; or, a minimum of two to three episodes of recurrent genitalis or cutaneous herpes simplex in immunocompromised patients.

The above will give you some idea of how unique the drug acyclovir is. The intravenous infusion formulation is available now (introduced in October 1982) and the oral capsule form is expected sometime in 1983. An ophthalmic ointment is under development.

Some people wonder why reduced viral shedding is necessary. Acyclovir does reduce time of viral shedding and this is important. The less time virus is given off from the lesion the less likely a person is to spread the disease, either to others or to other sites on his or her body. Acyclovir appears to be most useful for those individuals who manifest genital herpes disease symptoms for the first time. The clinical trials show a decrease in healing time and viral shedding in both men and women, and diminished pain in men. The person standing to gain the most benefit will be the exposed partner who develops signs and symptoms and consults with a physician early in the infection.

None of the clinical studies have given conclusive proof that acyclovir will prevent the virus from going into the latent stage even with early application of the drug. Since acyclovir cannot be counted on to prevent the latent infection stage, it follows that recurrent herpes infections will not be prevented either.

If you plan a purchase of Zovirax and price is a consideration, you might try calling several pharmacies in your area for price comparisons. The difference can be substantial in some areas. While in the drugstore be sure to purchase some finger cots or surgical rubber gloves with which to apply the ointment.

Intravenous Zovirax Facts

The following question and answer section is to acquaint you with the latest form of acyclovir—intravenous Zovirax.

How will intravenous Zovirax be used?

Intravenous Zovirax is a systemic treatment for serious HSV-1 and HSV-2 infections in hospitalized patients. It is approved for initial and recurrent HSV infections in adults and children whose natural defenses against infection are impaired, including cancer patients and organ transplant patients. Zovirax IV is also indicated for immune-normal

What therapeutic benefits does intravenous Zovirax offer?

Intravenous Zovirax speeds healing, reduces pain and stops the HSV from replicating. In immune-normal patients, the HSV usually causes painful, recurring genital sores or cold sores. In immune-suppressed patients, HSV infections can spread to vital organs and be fatal. Of the 200,000 reduced the median period over which virus was shed from 17 to 3 days, the median time to resolution of pain from 16 to 10 days and the median time to complete healing from 28 to 14 days. Such results are strong evidence for intravenous Zovirax providing life-saving therapy for these patients.

How does intravenous Zovirax work?

Zovirax attacks the virus selectively, leaving uninfected cells virtually unharmed. The drug becomes biologically active in virus-infected cells, where it is converted to its active form by a virus enzyme. In this form, Zovirax prevents the virus from replicating and spreading to other cells. By stopping virus replication, Zovirax speeds healing and reduces pain.

Is intravenous Zovirax a treatment or a cure?

Zovirax is used to manage active herpes virus infections. During the initial infection, the virus takes up residence in certain nerve cells and remains in the body in latent (inactive) form. Occasionally, the latent virus becomes active and causes recurrent outbreaks. There is no present evidence that Zovirax will eliminate the latent virus from the body, but when the virus begins actively replicating, Zovirax attacks it and controls its spread. In this sense, herpes infections are similar to hypertension, diabetes and many other diseases, which are not “cured” but managed with medications.

Does intravenous Zovirax prevent recurrent herpes infections?

Intravenous Zovirax has not been approved for prophylactic use. Studies are underway to determine whether it might be useful in preventing HSV infections in high-risk, immune-suppressed patients. Until these data are reviewed, it is not known whether intravenous Zovirax will be indicated for this use.

Can intravenous Zovirax be used to treat shingles?

Clinical studies are underway to test the use of intravenous Zovirax in a number of diseases caused b viruses in the herpes family, including shingles, which caused by varicella zoster virus. However, Zovirax is not approved for this indication. Until these data are reviewed, it is not known whether Zovirax will be indicated for shingles.

Is Zovirax available for herpes sufferers who are not hospital patients?

Because Zovirax IV is administered by intravenous“ infusion, its major use will be for hospital patients. Zovirax Ointment is available on prescription for the management of if less serious HSV infections. Zovirax Ointment is indicated for initial infections of genital herpes and for localized HSV-1 and HSV-2 infections of the skin of immune-suppressed patients

This is the treatment for herpes as we currently know it. The drug should shorten the course of an episode of herpes, but it is not a cure. You should take particular note that to another. It is unhealthy and can be dangerous to treat herpes or any other disease improperly. Do not believe everything the media presents to you. It seems hardly a week goes by that a “cure” for herpes doesn’t make the news. Be careful. Learn about herpes complications.

Zovirax - What It Is and How It Works
Article Name
Zovirax - What It Is and How It Works
Zovirax (acyclovir) Ointment 5% is the first effective drug for genital herpes, a sexually-transmitted disease that afflicts up to 20 million people in the United States. It is a breakthrough antiviral drug discovered and developed by Burroughs Welcome Co.

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