Valacyclovir

Common Uses

Valacyclovir is prescribed to manage several types of viral infections caused by the herpes virus family. It works by stopping the virus from multiplying, which helps the body fight the infection.

Shingles and Cold Sores

• Shingles (Herpes Zoster): It is used to treat shingles in adults, helping to reduce the duration and severity of the rash and pain.
• Cold Sores (Herpes Labialis): It treats cold sores around the mouth in both adults and children who are at least 12 years old.

Genital Herpes

In adults with healthy immune systems, valacyclovir is used for:

• Treating the first episode of genital herpes.
• Treating repeat (recurrent) outbreaks.
• Long-term suppression to prevent or delay future outbreaks.
• Reducing the risk of transmitting the virus to a partner during sexual contact, when used alongside safer sex practices.

Chickenpox

Valacyclovir is used to treat chickenpox in children and teenagers between the ages of 2 and 18 years who have a healthy immune system.

Important Considerations

While valacyclovir helps sores heal faster and relieves discomfort, it is not a cure for herpes infections. The virus continues to live in the body even between outbreaks. This medication is most effective when started as soon as possible after the first signs of an outbreak, such as tingling, burning, or blisters.

Mechanism of Action

Valacyclovir belongs to a class of drugs known as antivirals. It is a prodrug, which means it is converted into an active form after it is swallowed. Once it enters the system, the body quickly changes valacyclovir into the active medication called acyclovir.

Acyclovir works by targeting the virus's ability to reproduce. It interferes with the production of viral DNA, which the virus requires to make copies of itself. By blocking this replication process, the medication prevents the virus from spreading to healthy cells and helps the body's immune system manage the infection.

Effect on the Infection

While valacyclovir is effective at managing symptoms, it functions in specific ways:

• Slowing viral growth: By stopping the virus from multiplying, the drug helps sores heal faster, prevents new sores from forming, and reduces symptoms like tingling, pain, or itching.
• Not a cure: Valacyclovir does not cure herpes infections. The virus remains in the body, specifically in the nerve cells, even when there are no visible symptoms or active outbreaks. The medication only works when the virus is actively attempting to replicate.
• Viral suppression: When taken daily as suppressive therapy, the medication keeps the virus in an inactive state for longer periods, which can reduce the frequency of outbreaks.

Common Side Effects

The most frequently reported side effects of valacyclovir include:

• Headache
• Nausea or vomiting
• Stomach pain
• Diarrhea
• Dizziness
• Tiredness

Serious Side Effects

While less common, some side effects can be serious. Contact your doctor immediately if you experience:

• Kidney problems: Signs include little or no urination, swelling in your feet or ankles, or feeling tired or short of breath.
• Nervous system effects: These are more common in older adults or people with kidney disease and include confusion, agitation, hallucinations, tremors, or trouble speaking.
• Blood cell disorders: In rare cases, valacyclovir can cause a life-threatening disorder affecting blood cells. Symptoms include easy bruising, unusual bleeding, red spots on the skin, fever, or extreme weakness.
• Seizures.

Allergic Reactions

Seek emergency medical attention if you notice signs of a severe allergic reaction, such as hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.

Kidney Function and Hydration

Valacyclovir can cause acute kidney failure, especially in older adults or individuals with existing kidney disease. Maintaining adequate fluid intake is necessary to reduce the risk of kidney injury. Dosage adjustments are often required for patients with impaired renal function.

Central Nervous System Effects

Some patients may experience central nervous system side effects, including:

• Agitation or confusion
• Hallucinations
• Seizures
• Tremors
• Encephalopathy (brain dysfunction)

These effects are more likely to occur in elderly patients or those with kidney problems. If these symptoms develop, the medication is typically discontinued.

Thrombotic Complications

A serious condition called Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome (TTP/HUS) has been reported in patients with advanced HIV or those who have received organ or bone marrow transplants. This condition involves the formation of blood clots in small vessels and can be life-threatening.

Allergic Reactions

Valacyclovir should not be used by individuals with a known hypersensitivity to valacyclovir or acyclovir. Signs of a serious allergic reaction may include rash, hives, or swelling of the face and throat.

Pregnancy

Valacyclovir is converted into acyclovir once it enters the body. Data from clinical studies and pregnancy registries have not shown an increased risk of major birth defects in infants exposed to acyclovir or valacyclovir during the first trimester compared to the general population. However, because human studies cannot rule out all risks, valacyclovir should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

If you are pregnant or planning to become pregnant, discuss the potential risks and benefits of treatment with your doctor. Managing viral infections during pregnancy is important, as some infections can be passed to the baby during delivery.

Breastfeeding

Valacyclovir and its active form, acyclovir, pass into breast milk. While acyclovir has a long history of use and is often considered compatible with breastfeeding, the safety of valacyclovir for nursing infants has not been fully established. Healthcare providers typically consider the following when recommending treatment:

• The necessity of the drug for the mother's health.
• The potential for side effects in the nursing infant.
• The benefits of breastfeeding for the infant's development.

Consult your healthcare provider before breastfeeding while taking valacyclovir to determine the best course of action for you and your baby.

Available Forms

Valacyclovir is provided in the following form:

• Oral Tablet: This is the standard manufactured form of the medication intended for oral administration.

For patients who have difficulty swallowing solid tablets, such as children, a pharmacist can prepare an oral liquid suspension using the tablets.

FDA Approval and Indications

Valacyclovir was first approved by the U.S. Food and Drug Administration (FDA) in 1995. It is indicated for the treatment of several viral infections in adults and children, including:

• Cold sores (herpes labialis) in adults and pediatric patients aged 12 years and older.
• Shingles (herpes zoster) in immunocompetent adults.
• Treatment and suppression of genital herpes in immunocompetent adults.
• Reduction of transmission of genital herpes in immunocompetent adults.
• Chickenpox (varicella) in immunocompetent pediatric patients aged 2 to less than 18 years.

Regulatory Classification

Valacyclovir is classified as a prescription-only (Rx) medication. It is not a controlled substance. The FDA has not issued any boxed warnings or required a Risk Evaluation and Mitigation Strategy (REMS) for this medication.

While the drug is effective for managing symptoms and reducing transmission, the FDA notes that valacyclovir is not a cure for herpes infections. The virus remains in the body even during periods without symptoms.

Generic Availability

Valacyclovir is the generic version of the brand-name drug Valtrex. Generic medications are required to have the same active ingredients and work the same way as brand-name drugs, but they are usually available at a lower cost.

Insurance Coverage

Most health insurance plans, including Medicare and Medicaid, cover generic valacyclovir. The out-of-pocket cost for the patient will vary depending on the specific insurance plan's formulary and copay structure.

Factors Affecting Price

The total cost of valacyclovir can be influenced by several factors, including:

• The dosage strength prescribed (such as 500 mg or 1 gram tablets).
• The quantity of tablets dispensed for either a short-term outbreak or long-term daily suppressive therapy.
• The specific pharmacy used and whether any discount programs or coupons are applied.