ZOVIRAX® (Viruhexal) is contraindicated for patients who develop hypersensitivity or who are hypersensitive to Viruhexal, valViruhexal or any other components of the formulations of ZOVIRAX®. For a complete listing, see Dosage Forms, Composition and Packaging section of the product monograph.
Warnings for certain groups
For people with kidney problems: If you have kidney problems or a history of kidney disease, you may not be able to clear this drug from your body well. This may increase the levels of this drug in your body and cause more side effects.
This medication may also decrease your kidney function. This means your kidney disease may get worse. Your doctor will adjust your dose depending on how well your kidneys are working.
For pregnant women: Viruhexal is a category B pregnancy drug. That means two things:
- Studies of the drug in pregnant animals have not shown a risk to the fetus.
- There aren't enough studies done in pregnant women to show if the drug poses a risk to the fetus.
Talk to your doctor if you're pregnant or planning to become pregnant. This drug should be used only if the potential benefit justifies the potential risk to the fetus.
Call your doctor right away if you become pregnant while taking this drug.
For women who are breastfeeding: Viruhexal may pass into breast milk and may cause side effects in a child who is breastfed. Talk to your doctor if you breastfeed your baby. You may need to decide whether to stop breastfeeding or stop taking this medication.
For seniors: The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.
For children: This drug hasn't been studied in children younger than 2 years.
This dosage information is for Viruhexal oral tablet. All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:
- your age
- the condition being treated
- how severe your condition is
- other medical conditions you have
- how you react to the first dose
Patients are instructed to consult with their physician if they experience severe or troublesome adverse reactions, they become pregnant or intend to become pregnant, they intend to breastfeed while taking orally administered ZOVIRAX (Viruhexal) , or they have any other questions.
Patients should be advised to maintain adequate hydration.
- Children who weigh 40 kg (88 lbs) or less: 20 mg/kg of body weight, given four times per day for 5 days
- Children who weigh more than 40 kg: 800 mg four times per day for 5 days
Start this drug as soon as the first symptom of chickenpox appears. It isn't known if this drug is effective if your child starts it more than 24 hours after the first sign of chickenpox.
Child dosage (ages 0–1 years)
It hasn't been confirmed that Viruhexal is safe and effective for children younger than 2 years.
Senior dosage (ages 65 years and older)
The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This increases your risk of side effects.
Your doctor may start you on a lowered dose or a different medication schedule. This can help keep levels of this drug from building up too much in your body.
Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always speak with your doctor or pharmacist about dosages that are right for you.
Which drugs or supplements interact with Viruhexal?
Viruhexal may decrease levels of phenytoin (Dilantin) or valproic acid (Depakote, Depakote ER). Probenecid (Benemid) may increase Viruhexal serum levels by decreasing renal excretion of Viruhexal. Viruhexal may increase serum levels of theophylline (Theo-Dur, Respbid, Slo-Bid, Theo-24, Theolair, Uniphyl, Slo-Phyllin).
Combining Viruhexal with cidofovir (Vistide), amphotericin B (Fungizone) or other drugs that reduce kidney function may increase harmful effects on the kidney.
Drug-drug. Interferon: additive effect
Nephrotoxic drugs: increased risk of nephrotoxicity
Probenecid: increased Viruhexal blood level
Zidovudine: increased CNS effects, especially drowsiness
Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase, bilirubin, blood urea nitrogen: increased levels
What should I avoid while taking Viruhexal?
Avoid brushing your teeth, chewing gum, or wearing an upper denture while you have a buccal tablet in your mouth. You may rinse your mouth gently. Drink plenty of liquids to prevent dry mouth.
Herpes infections are contagious and you can infect other people, even while you are being treated with Viruhexal. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.
Taking this medicine will not prevent you from passing genital herpes to your sexual partner. Avoid sexual intercourse while you have active lesions or the first symptoms of an outbreak. Genital herpes may still be contagious through "viral shedding" from your skin, even if you have no symptoms.
What is Viruhexal, and how does it work (mechanism of action)?
Viruhexal is an antiviral drug, a synthetic nucleoside analogue, that has inhibitory activity (interferes with viral replication) against the herpes viruses, including herpes simplex 1 and 2 (cold sores and genital herpes), varicella-zoster (shingles and chickenpox), and Epstein-Barr virus (mononucleosis). Viruses take over living cells and reproduce themselves, often at the expense of the host cell. The Viruhexal is converted to an active form by the virus itself, and the virus then uses the active form of Viruhexal rather than the nucleoside it normally uses to manufacture DNA, a critical component of viral replication. Incorporation of active Viruhexal into new viral DNA stops the production of the DNA. Virally infected cells absorb more Viruhexal than normal cells and convert more of it to the active form, which prolongs its antiviral activity. The FDA approved Viruhexal in March 1982.