Zovirax

Zovirax is a brand name of an antiviral drug called acyclovir. Zovirax (acyclovir) slows the growth and spread of the herpes and varicella-zoster virus in the body. Zovirax (acyclovir) will not cure herpes, but it can lessen the symptoms of the infection. Zovirax (acyclovir) is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox.

Zovirax (acyclovir) is available only with your doctor’s prescription.

Zovirax (acyclovir) is indicated for therapy of localized as well as disseminated herpes simplex infections, both type 1 and 2 herpes simplex infections. Zovirax (acyclovir) is also used for varicella-zoster infections (chickenpox and shingles). Zovirax (acyclovir) was approved for use in herpes virus infections in the United States in 1982, and is still widely used in treatment and prophylaxis of genital and mucocutaneous herpes simplex infection with almost 5 million prescriptions filled yearly.

Zovirax (acyclovir) is an acyclic purine nucleoside analogue (acycloguanosine) which has antiviral activity against many herpes viruses, including herpes simplex 1 and 2, cytomegalovirus, Ebstein-Barr virus and varicella-zoster. Zovirax (acyclovir) is phosphorylated intracellularly by viral kinases, and the resultant triphosphate competes with guanosine for incorporation into viral DNA blocking viral DNA polymerase activity.

Acyclovir is available as capsules of 200 mg, tablets of 400 and 800 mg, oral suspensions, creams, ointments, and parenteral preparations in several generic forms, as well as under the brand name of Zovirax. The typical recommended oral dose in adults for genital or oral herpes simplex is 200 to 800 mg three to five times daily for 5 to 10 days; the usual prophylactic dose is 400 mg twice daily. The typical intravenous doses for severe infections is 5 to 10 mg/kg every 8 hours for 5 to 10 days.

Zovirax (acyclovir) side effects are uncommon with oral formulations, but can include myalgias, rash, temors, lethargy and confusion. Rare side effects include bone marrow toxicity and Stevens Johnson syndrome.

Zovirax uses

Zovirax (acyclovir) is used to decrease pain and speed the healing of sores or blisters in people who have varicella (chickenpox), herpes zoster (shingles; a rash that can occur in people who have had chickenpox in the past), and first-time or repeat outbreaks of genital herpes (a herpes virus infection that causes sores to form around the genitals and rectum from time to time). Zovirax (acyclovir) is also sometimes used to prevent outbreaks of genital herpes in people who are infected with the virus. Zovirax (acyclovir) works by stopping the spread of the herpes virus in the body.  Zovirax (acyclovir) will not cure genital herpes and may not stop the spread of genital herpes to other people.

Zovirax (acyclovir) is also sometimes used to treat eczema herpeticum (a skin infection caused by the herpes virus) to treat and prevent herpes infections of the skin, eyes, nose, and mouth in patients with human immunodeficiency virus (HIV), and to treat oral hairy leukoplakia (condition that causes hairy white or gray-colored patches on the tongue or inside of the cheek).

Zovirax topical uses

Zovirax (acyclovir) cream is used to treat cold sores (fever blisters; blisters that are caused by a virus called herpes simplex) on the face or lips. Zovirax (acyclovir) ointment is used to treat first outbreaks of genital herpes (a herpes virus infection that causes sores to form around the genitals and rectum from time to time) and to treat certain types of sores caused by the herpes simplex virus in people with weak immune systems. Zovirax (acyclovir) is in a class of antiviral medications called synthetic nucleoside analogues. It works by stopping the spread of the herpes virus in the body. Zovirax (acyclovir) does not cure cold sores or genital herpes, does not prevent outbreaks of these conditions, and does not stop the spread of these conditions to other people.

How should topical Zovirax be used?

Topical Zovirax (acyclovir) comes as a cream and an ointment to apply to the skin. Zovirax (acyclovir) cream is usually applied five times a day for 4 days. Zovirax (acyclovir) cream may be applied at any time during a cold sore outbreak, but it works best when it is applied at the very beginning of a cold sore outbreak, when there is tingling, redness, itching, or a bump but the cold sore has not yet formed. Zovirax (acyclovir) ointment is usually applied six times a day (usually 3 hours apart) for 7 days. It is best to begin using Zovirax (acyclovir) ointment as soon as possible after you experience the first symptoms of infection. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Use topical Zovirax (acyclovir) exactly as directed. Do not use more or less of it or use it more often than prescribed by your doctor.

Your symptoms should improve during your treatment with topical Zovirax (acyclovir). If your symptoms do not improve or if they get worse, call your doctor.

Zovirax (acyclovir) cream and ointment are for use only on the skin. Do not let Zovirax (acyclovir) cream or ointment get into your eyes, or inside your mouth or nose, and do not swallow the medication.

Zovirax (acyclovir) cream should only be applied to skin where a cold sore has formed or seems likely to form. Do not apply Zovirax (acyclovir) cream to any unaffected skin, or to genital herpes sores.

Do not apply other skin medications or other types of skin products such as cosmetics, sun screen, or lip balm to the cold sore area while using Zovirax (acyclovir) cream unless your doctor tells you that you should.

To use Zovirax (acyclovir) cream, follow these steps:

1. Wash your hands.
2. Clean and dry the area of skin where you will be applying the cream.
3. Apply a layer of cream to cover the skin where the cold sore has formed or seems likely to form.
4. Rub the cream into the skin until it disappears.
5. Leave the skin where you applied the medication uncovered. Do not apply a bandage or dressing unless your doctor tells you that you should.
6. Wash your hands with soap and water to remove any cream left on your hands.
7. Be careful not to wash the cream off of your skin. Do not bathe, shower, or swim right after applying Zovirax (acyclovir) cream.
8. Avoid irritation of the cold sore area while using Zovirax (acyclovir) cream.

To use Zovirax (acyclovir) ointment, follow these steps:

1. Put on a clean finger cot or rubber glove.
2. Apply enough ointment to cover all of your sores.
3. Take off the finger cot or rubber glove and dispose of it safely, so that it is out of reach of children.
4. Keep the affected area(s) clean and dry, and avoid wearing tight-fitting clothing over the affected area.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. Read this information before you start using Zovirax (acyclovir) and each time you refill your prescription.

Zovirax special precautions

Before taking Zovirax (acyclovir):

• tell your doctor and pharmacist if you are allergic to acyclovir, valacyclovir (Valtrex), any other medications, or any of the ingredients in acyclovir. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: amphotericin B (Fungizone); aminoglycoside antibiotics such as amikacin (Amikin), gentamicin (Garamycin), kanamycin (Kantrex), neomycin (Nes-RX, Neo-Fradin), paramomycin (Humatin), streptomycin, and tobramycin (Tobi, Nebcin); aspirin and other nonsteroidal anti-inflammatory drugs such as ibuprofen (Advil, Motrin), and naproxen (Aleve, Naprosyn); cyclosporine (Neoral, Sandimmune); medications to treat HIV or AIDS such as zidovudine (Retrovir, AZT); pentamidine (NebuPent); probenecid (Benemid); sulfonamides such as sulfamethoxazole and trimethoprim (Bactrim); tacrolimus (Prograf); and vancomycin. Many other medications may also interact with acyclovir, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if there is a possibility you may be dehydrated from a recent illness or activity, or if you have or have ever had problems with your immune system; human immunodeficiency virus infection (HIV); acquired immunodeficiency syndrome (AIDS); or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking acyclovir, call your doctor.
• if you are taking acyclovir to treat genital herpes, you should know that genital herpes can be spread through sexual contact even if you don’t have blisters or other symptoms and possibly even if you are taking acyclovir. Talk to your doctor about ways to stop the spread of genital herpes and about whether your partner(s) should receive treatment.

Geriatric

Agitation, confusion, dizziness, and drowsiness may be especially likely to occur in elderly patients who are usually more sensitive than younger adults to the central nervous system effects of acyclovir.

Pregnancy

Pregnancy Category B: Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate studies in pregnant women OR animal studies have shown an adverse effect, but adequate studies in pregnant women have failed to demonstrate a risk to the fetus.

Breastfeeding

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking Zovirax (acyclovir), it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using Zovirax (acyclovir) with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Foscarnet
• Tolvaptan

Using Zovirax (acyclovir) with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Fosphenytoin
• Phenytoin
• Valproic Acid

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of Zovirax (acyclovir). Make sure you tell your doctor if you have any other medical problems, especially:

• Dehydration or
• Kidney disease—Dehydration or kidney disease may increase blood levels of acyclovir, increasing the chance of side effects.
• Nervous system problems—Acyclovir may make these problems worse.

Zovirax dosage

Zovirax (acyclovir) is best used as soon as possible after the symptoms of herpes infection or shingles (for example, pain, burning, blisters) begin to appear.

If you are taking Zovirax (acyclovir) for the treatment of chickenpox, it is best to start taking Zovirax (acyclovir) as soon as possible after the first sign of the chickenpox rash, usually within one day.

Zovirax (acyclovir) capsules, tablets, and oral suspension may be taken with meals or on an empty stomach.

Zovirax (acyclovir) is best taken with a full glass (8 ounces) of water.

If you are using Zovirax (acyclovir) oral suspension, use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

To help clear up your herpes infection, chickenpox, or shingles, keep taking Zovirax (acyclovir) for the full time of treatment, even if your symptoms begin to clear up after a few days. Do not miss any doses. However, do not use this medicine more often or for a longer time than your doctor ordered.

If you are taking Zovirax (acyclovir) capsules, tablets, or oral suspension, you should drink plenty of water to avoid becoming dehydrated.

Acute treatment of Herpes Zoster

• 800 mg every 4 hours orally, 5 times daily for 7 to 10 days.

Genital Herpes

• Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.
• Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
• Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.

The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with Zovirax.

Treatment of Chickenpox

• Children (2 years of age and older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
• Adults and Children over 40 kg: 800 mg 4 times daily for 5 days.

Intravenous Zovirax is indicated for the treatment of varicella-zoster infections in immunocompromised patients.

When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.

Patients with acute or chronic renal impairment

In patients with renal impairment, the dose of Zovirax Capsules, Tablets, or Suspension should be modified as shown in Table 1.

Table 1. Zovirax dosage modification for renal impairment

Hemodialysis

For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.

Peritoneal Dialysis

No supplemental dose appears to be necessary after adjustment of the dosing interval.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it and take any remaining doses for that day at evenly spaced intervals. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Zovirax side effects

Zovirax (acyclovir) may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• upset stomach
• vomiting
• diarrhea
• dizziness
• tiredness
• agitation
• pain, especially in the joints
• hair loss
• changes in vision

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

• hives
• rash or blisters
• itching
• difficulty breathing or swallowing
• swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
• hoarseness
• fast heartbeat
• weakness
• pale skin
• difficulty sleeping
• fever, sore throat, chills, cough, and other signs of infection
• unusual bruising or bleeding
• blood in the urine
• stomach pain or cramps
• bloody diarrhea
• decreased urination
• headache
• hallucinations (seeing things or hearing voices that do not exist)
• confusion
• aggressive behavior
• difficulty speaking
• numbness, burning, or tingling in the arms or legs
• temporary inability to move parts of your body
• shaking of a part of your body that you cannot control
• seizures
• loss of consciousness

Zovirax (acyclovir) may cause other side effects. Call your doctor if you have any unusual problems while you are taking Zovirax (acyclovir).

Symptoms of Zovirax (acyclovir) overdose may include:

• agitation
• seizures
• extreme tiredness
• loss of consciousness
• swelling of the hands, feet, ankles, or lower legs
• decreased urination

Topical Zovirax (acyclovir) may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• dry or cracked lips
• flaky, peeling, or dry skin
• burning or stinging skin
• redness, swelling, or irritation in the place where you applied the medication

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

• hives
• rash
• itching
• difficulty breathing or swallowing
• swelling of the face, throat, lips, eyes, hands, feet, ankles, or lower legs
• hoarseness

Topical Zovirax (acyclovir) may cause other side effects. Call your doctor if you have any unusual problems while using topical Zovirax (acyclovir).