Valacyclovir 500mg Tablets
It is used to treat shingles, cold sores, or certain other herpes infections.It is used to treat chickenpox.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antiviral
Pharmacologic Class
Guanosine nucleoside analog; DNA polymerase inhibitor
Pregnancy Category
Category B
FDA Approved
Dec 1995
DEA Schedule
Not Controlled
Overview
What is this medicine?
Valacyclovir is an antiviral medicine used to treat infections caused by certain types of viruses, such as herpes simplex (cold sores, genital herpes) and herpes zoster (shingles). It works by stopping the growth and spread of the virus in the body. It does not cure herpes infections but helps to reduce the severity and duration of outbreaks.
How to Use This Medicine
Taking Your Medication
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided to you and follow the instructions closely. You can take this medication with or without food. Unless your doctor advises you to limit your fluid intake, be sure to drink plenty of non-caffeinated liquids.
If you are taking this medication to treat cold sores, chickenpox, shingles, or genital herpes, start taking it as soon as symptoms appear. The sooner you start, the more effective the medication will be. If you delay taking the medication, it may not work as well.
If you are undergoing dialysis and take this medication on the day of your dialysis, take it after your dialysis treatment. If you have any questions or concerns, discuss them with your doctor.
Continue taking this medication as directed by your doctor or healthcare provider, even if you start to feel better.
Special Instructions for Liquid (Suspension) Formulation
If you have trouble swallowing pills, your doctor or pharmacist can prepare a liquid (suspension) formulation for you. Before using the liquid formulation, shake the bottle well. To ensure accurate dosing, use the measuring device provided with the medication. If no device is provided, ask your pharmacist for a suitable measuring device.
Storing and Disposing of Your Medication
Tablets: Store at room temperature in a dry place, away from the bathroom.
Liquid (suspension): Store according to the instructions provided by your doctor or pharmacist.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take two doses at the same time or take extra doses.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided to you and follow the instructions closely. You can take this medication with or without food. Unless your doctor advises you to limit your fluid intake, be sure to drink plenty of non-caffeinated liquids.
If you are taking this medication to treat cold sores, chickenpox, shingles, or genital herpes, start taking it as soon as symptoms appear. The sooner you start, the more effective the medication will be. If you delay taking the medication, it may not work as well.
If you are undergoing dialysis and take this medication on the day of your dialysis, take it after your dialysis treatment. If you have any questions or concerns, discuss them with your doctor.
Continue taking this medication as directed by your doctor or healthcare provider, even if you start to feel better.
Special Instructions for Liquid (Suspension) Formulation
If you have trouble swallowing pills, your doctor or pharmacist can prepare a liquid (suspension) formulation for you. Before using the liquid formulation, shake the bottle well. To ensure accurate dosing, use the measuring device provided with the medication. If no device is provided, ask your pharmacist for a suitable measuring device.
Storing and Disposing of Your Medication
Tablets: Store at room temperature in a dry place, away from the bathroom.
Liquid (suspension): Store according to the instructions provided by your doctor or pharmacist.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take two doses at the same time or take extra doses.
Lifestyle & Tips
- Stay well-hydrated, especially during treatment, to help prevent kidney problems.
- This medication does not prevent the spread of herpes to others. Practice safe sex (e.g., use condoms) and avoid sexual contact during outbreaks.
- Avoid sharing personal items that may spread the virus (e.g., lip balm, eating utensils during cold sore outbreaks).
- Complete the full course of medication as prescribed, even if symptoms improve.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Varies by indication. Examples: Herpes Zoster: 1000 mg three times daily for 7 days; Genital Herpes (recurrent): 500 mg twice daily for 3 days; Herpes Labialis: 2000 mg twice daily for 1 day.
Dose Range:
500 - 1000 mg
Condition-Specific Dosing:
Herpes Zoster (Shingles):
1000 mg three times daily for 7 days
Genital Herpes (Initial Episode):
1000 mg twice daily for 7-10 days
Genital Herpes (Recurrent Episode):
500 mg twice daily for 3 days
Genital Herpes (Suppressive Therapy):
1000 mg once daily (or 500 mg once daily for patients with <9 recurrences/year)
Herpes Labialis (Cold Sores):
2000 mg twice daily for 1 day
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Chickenpox (2 to <18 years): 20 mg/kg (max 1000 mg) three times daily for 5 days
Adolescent:
Herpes Labialis (âĨ12 years): 2000 mg twice daily for 1 day
Dose Adjustments
Renal Impairment:
Mild:
CrCl 30-49 mL/min: Dose reduction required for some indications (e.g., Zoster: 1000 mg twice daily; Genital Herpes suppression: 500 mg once daily).
Moderate:
CrCl 10-29 mL/min: Further dose reduction required (e.g., Zoster: 1000 mg once daily; Genital Herpes suppression: 500 mg every other day).
Severe:
CrCl <10 mL/min: Significant dose reduction required (e.g., Zoster: 500 mg once daily; Genital Herpes suppression: 500 mg every 3 days).
Dialysis:
Hemodialysis: Administer after hemodialysis. Peritoneal dialysis: Dosing similar to CrCl <10 mL/min.
Hepatic Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed (pharmacokinetics of acyclovir are not significantly altered)
Pharmacology
Mechanism of Action
Valacyclovir is a prodrug of acyclovir. It is rapidly and extensively converted to acyclovir and L-valine by first-pass intestinal and hepatic metabolism. Acyclovir is then phosphorylated to acyclovir monophosphate by viral thymidine kinase, then to acyclovir triphosphate by cellular kinases. Acyclovir triphosphate inhibits viral DNA synthesis and replication by competing with deoxyguanosine triphosphate for incorporation into viral DNA, leading to chain termination and inactivation of viral DNA polymerase.
Pharmacokinetics
Absorption:
Bioavailability:
54%
Tmax:
1-2 hours (for acyclovir)
FoodEffect:
Food generally does not affect the extent of absorption of valacyclovir.
Distribution:
Vd:
0.8 L/kg (for acyclovir)
ProteinBinding:
13-33% (for acyclovir)
CnssPenetration:
Yes (CSF levels are approximately 50% of plasma levels)
Elimination:
HalfLife:
2.5-3.3 hours (for acyclovir, with normal renal function)
Clearance:
Not available (primarily renal clearance of acyclovir)
ExcretionRoute:
Renal (glomerular filtration and tubular secretion)
Unchanged:
Not available (valacyclovir is extensively converted; acyclovir is excreted largely unchanged)
Pharmacodynamics
OnsetOfAction:
Not precisely defined (antiviral effect is on viral replication)
PeakEffect:
Not precisely defined (related to viral load reduction over time)
DurationOfAction:
Related to dosing frequency and viral replication cycle
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of kidney problems, including:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Confusion
Changes in behavior
Mood changes
Hallucinations (seeing or hearing things that are not there)
Difficulty speaking
Shakiness, trouble moving around, or stiffness
Seizures
Signs of severe and potentially life-threatening blood problems, such as:
+ Feeling extremely tired or weak
+ Bruising or bleeding
+ Dark urine or yellow skin and eyes
+ Pale skin
+ Changes in urine output
+ Changes in vision
+ Weakness or numbness on one side of the body
+ Trouble speaking or thinking
+ Balance problems
+ Fever
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
Headache
Upset stomach or vomiting
Stomach pain
Diarrhea
Feeling tired or weak
Menstrual pain
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of kidney problems, including:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Confusion
Changes in behavior
Mood changes
Hallucinations (seeing or hearing things that are not there)
Difficulty speaking
Shakiness, trouble moving around, or stiffness
Seizures
Signs of severe and potentially life-threatening blood problems, such as:
+ Feeling extremely tired or weak
+ Bruising or bleeding
+ Dark urine or yellow skin and eyes
+ Pale skin
+ Changes in urine output
+ Changes in vision
+ Weakness or numbness on one side of the body
+ Trouble speaking or thinking
+ Balance problems
+ Fever
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
Headache
Upset stomach or vomiting
Stomach pain
Diarrhea
Feeling tired or weak
Menstrual pain
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of kidney problems (e.g., little or no urination, painful urination, swelling in your feet or ankles, feeling tired or short of breath)
- Signs of central nervous system effects (e.g., confusion, agitation, hallucinations, unusual thoughts or behavior, seizures, tremors, slurred speech)
- Signs of a severe allergic reaction (e.g., rash, hives, difficulty breathing, swelling of your face, lips, tongue, or throat)
- Unusual bruising or bleeding, purple or red spots under your skin (may indicate thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, rare but serious side effect)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
Potential interactions with other medications or health conditions. This drug may interact with other prescription or over-the-counter (OTC) medications, natural products, or vitamins, which could affect its safety and efficacy.
All medications you are currently taking, including prescription and OTC medications, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions and ensure safe use.
Any existing health problems, as they may impact the safety and effectiveness of this medication.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is crucial to verify that it is safe to take this medication with all your other medications and health conditions.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
Potential interactions with other medications or health conditions. This drug may interact with other prescription or over-the-counter (OTC) medications, natural products, or vitamins, which could affect its safety and efficacy.
All medications you are currently taking, including prescription and OTC medications, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions and ensure safe use.
Any existing health problems, as they may impact the safety and effectiveness of this medication.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is crucial to verify that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Adhere to your doctor's prescribed treatment duration and do not exceed it. If you are using this drug to manage cold sores, be aware that it will not provide a cure for the condition. Consult with your doctor to discuss the treatment's limitations.
This medication is not a cure for herpes infections, and it is crucial to discuss its effects with your doctor. If you have genital herpes, note that this drug will not prevent the spread of the infection. To minimize the risk of transmission, avoid any form of sexual activity when you have active sores or other symptoms of genital herpes. It is also important to recognize that genital herpes can be spread even in the absence of visible symptoms. Always use a latex or polyurethane condom during sexual activity and consult with your doctor for guidance.
If you are 65 years or older, exercise caution when using this medication, as you may be more susceptible to side effects. Pregnant women, those planning to become pregnant, or breastfeeding mothers should inform their doctor, as it is necessary to discuss the potential benefits and risks of this medication to both the mother and the baby.
This medication is not a cure for herpes infections, and it is crucial to discuss its effects with your doctor. If you have genital herpes, note that this drug will not prevent the spread of the infection. To minimize the risk of transmission, avoid any form of sexual activity when you have active sores or other symptoms of genital herpes. It is also important to recognize that genital herpes can be spread even in the absence of visible symptoms. Always use a latex or polyurethane condom during sexual activity and consult with your doctor for guidance.
If you are 65 years or older, exercise caution when using this medication, as you may be more susceptible to side effects. Pregnant women, those planning to become pregnant, or breastfeeding mothers should inform their doctor, as it is necessary to discuss the potential benefits and risks of this medication to both the mother and the baby.
Overdose Information
Overdose Symptoms:
- Increased side effects such as nausea, vomiting, diarrhea, headache, dizziness, confusion, hallucinations, seizures, kidney failure (e.g., decreased urine output).
What to Do:
Seek immediate medical attention or call a Poison Control Center (1-800-222-1222). Hemodialysis can remove acyclovir from the blood.
Drug Interactions
Major Interactions
- Mycophenolate mofetil (increased exposure of mycophenolic acid)
- Nephrotoxic drugs (e.g., aminoglycosides, NSAIDs, cyclosporine, tacrolimus, foscarnet, amphotericin B - increased risk of renal toxicity)
Moderate Interactions
- Cimetidine (may increase acyclovir AUC by reducing renal clearance)
- Probenecid (may increase acyclovir AUC by reducing renal clearance)
Monitoring
Baseline Monitoring
Renal function (BUN, serum creatinine, CrCl)
Rationale: Valacyclovir (acyclovir) is primarily renally eliminated; dose adjustment is required in renal impairment.
Timing: Prior to initiation, especially in elderly patients or those with pre-existing renal dysfunction.
Routine Monitoring
Renal function (BUN, serum creatinine)
Frequency: Periodically, especially in patients with renal impairment, elderly patients, or those receiving concomitant nephrotoxic agents.
Target: Within patient's baseline or normal limits.
Action Threshold: Significant increase in BUN/creatinine warrants dose adjustment or discontinuation.
Signs and symptoms of CNS adverse effects (e.g., confusion, hallucinations, agitation, seizures)
Frequency: Throughout therapy, especially in elderly patients or those with renal impairment.
Target: Absence of new or worsening neurological symptoms.
Action Threshold: Development of new or worsening CNS symptoms warrants immediate evaluation and potential dose reduction or discontinuation.
Symptom Monitoring
- Nausea
- Vomiting
- Diarrhea
- Headache
- Dizziness
- Fatigue
- Abdominal pain
- Rash
- Confusion
- Hallucinations
- Agitation
- Seizures
- Kidney pain (flank pain)
- Decreased urination
Special Patient Groups
Pregnancy
Category B. Studies in animals have not shown a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. Acyclovir (the active metabolite) is generally considered safe for use during pregnancy for severe or life-threatening herpes infections, and for suppression in late pregnancy to prevent neonatal herpes.
Trimester-Specific Risks:
First Trimester:
Generally considered low risk; use if clearly needed.
Second Trimester:
Generally considered low risk; use if clearly needed.
Third Trimester:
Generally considered low risk; often used for suppression in late pregnancy to prevent neonatal herpes.
Lactation
L2 (Safer). Acyclovir is excreted into breast milk in low concentrations. The amount ingested by a breastfed infant is generally considered to be low and unlikely to cause adverse effects. Monitor infant for diarrhea or rash.
Infant Risk:
Low risk. Monitor for potential adverse effects such as diarrhea or rash in the infant.
Pediatric Use
Dosing established for specific indications (e.g., chickenpox in children 2 to <18 years, herpes labialis in adolescents âĨ12 years). Safety and efficacy not established in children younger than 12 years for genital herpes or younger than 2 years for chickenpox.
Geriatric Use
Increased risk of renal impairment and CNS adverse events (e.g., confusion, hallucinations) due to age-related decline in renal function. Dose adjustment based on creatinine clearance is crucial. Start with lower doses and monitor closely.
Clinical Information
Clinical Pearls
- Valacyclovir is a prodrug of acyclovir, offering improved bioavailability and less frequent dosing compared to acyclovir.
- Adequate hydration is important during treatment to prevent renal crystallization, especially with higher doses or in patients with pre-existing renal impairment.
- It is crucial to adjust the dose in patients with renal impairment to prevent accumulation and potential neurotoxicity.
- Valacyclovir does not cure herpes infections and does not prevent transmission to others. Patients should be counseled on safe sex practices.
- For recurrent genital herpes, initiating treatment at the first sign or symptom of an outbreak is key for optimal efficacy.
Alternative Therapies
- Acyclovir (oral, IV, topical)
- Famciclovir (oral)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic 500mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.