Valacyclovir Has A Higher Oral Bioavailability Than Acyclovir
One of the major benefits of Valacyclovir vs Acyclovir is its increased oral bioavailability. Meaning, it can get into your system much more than Acyclovir when taken as an oral tablet.
When Valacyclovir is taken by mouth, it is rapidly converted into Acyclovir in the body, leading to a 3-5 fold increase in the amount of Acyclovir bioavailable in the body than if you had taken oral Acyclovir.
What Is Valtrex Used For
The Food and Drug Administration approved Valtrex for the following indications:
- Genital herpes, usually caused by herpes simplex virus 2
- Prevention of transmission of HSV
- Suppression of HSV
- Suppression of HSV for people who are immunosuppressed due to human immunodeficiency virus
- Shingles, which is caused by reactivation of varicella zoster and produces a painful rash
The dosing of Valtrex differs for children and adults and is based on weight for the treatment of chicken pox. Valtrex is used short term for the treatment of chicken pox, shingles, and cold sores.
It can also be used for the short-term treatment of genital herpes or long term to suppress the virus and prevent transmission to a partner. However, it is important to remember that Valtrex will not cure your herpes infection completely.
Genital Herpes Guide: Treatment And Follow
Treatment and follow-up guidance for the genital herpes.
Note: This guide provides minimal information about neonatal herpes. For more information, refer to the Canadian Paediatric Society Position Statement about the prevention and management of neonatal herpes simplex virus infections.
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How Should I Take Valacyclovir Tablets
- Take valacyclovir tablets exactly as prescribed by your healthcare provider. Your dose of valacyclovir tablets and length of treatment will depend on the type of herpes infection that you have and any other medical problems that you have.
- Do not stop valacyclovir tablets or change your treatment without talking to your healthcare provider.
- Valacyclovir tablets can be taken with or without food.If you are taking valacyclovir tablets to treat cold sores, chickenpox, shingles or genital herpes, you should start treatment as soon as possible after your symptoms start. Valacyclovir tablets may not help you if you start treatment too late.
- If you miss a dose of valacyclovir tablets, take it as soon as you remember and then take your next dose at its regular time. However, if it is almost time for your next dose, do not take the missed dose. Wait and take the next dose at the regular time.
- Do not take more than the prescribed number of valacyclovir tablets each day. Call your healthcare provider right away if you take too much valacyclovir tablets.
Warnings For People With Certain Health Conditions
For people with kidney problems: Your kidneys clear this drug from your body. If you have kidney problems or a history of kidney disease, you may not be able to clear it from your body. This may increase the levels of the drug in your body and cause more side effects. This drug can also make your kidney function worse. To help prevent these problems, your doctor may prescribe a lower dosage of this drug for you.
For people with advanced HIV or a history of transplant: If you have advanced HIV or a history of bone marrow or kidney transplant, you may be at a higher risk of certain blood disorders. These conditions are called thrombocytopenic purpura and hemolytic uremic syndrome . They can result in severely low red blood cells and platelets in your body. TTP or HUS can cause death.
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What Is Valtrex What Is Zovirax
Valtrex is a type of antiviral drug called a nucleoside analog used to treat infections with shingles , genital herpes , and cold sores . Nucleoside analogs mimic one of the building blocks of DNA and they stop the spread of the herpes virus by preventing the viral DNA replication that is necessary for viruses to multiply. Acyclovir and famciclovir are also nucleoside analogs. Valacyclovir is called a “prodrug,” in that it is not active itself but rather, it is converted to acyclovir in the body, and it is the acyclovir that is active against the viruses. Valtrex thus is active against the same viruses as acyclovir, but Valtrex has a longer duration of action than acyclovir and can be taken fewer times each day.
Zovirax is an antiviral drug, a synthetic nucleoside analogue, that has inhibitory activity against the herpes viruses, including herpes simplex 1 and 2 , varicella-zoster , and Epstein-Barr virus . Viruses take over living cells and reproduce themselves, often at the expense of the host cell. Zovirax is converted to an active form by the virus itself, and the virus then uses the active form of acyclovir rather than the nucleoside it normally uses to manufacture DNA, a critical component of viral replication. Incorporation of active acyclovir into new viral DNA stops the production of the DNA. Virally infected cells absorb more Zovirax than normal cells and convert more of it to the active form, which prolongs its antiviral activity.
Patients With Renal Impairment
Dosage recommendations for adult patients with reduced renal function are provided in Table 1 .Data are not available for the use of Valacyclovir in pediatric patients with a creatinine clearance less than 50 mL/min/1.73 m 2.
Table 1. Valacyclovir Dosage Recommendations for Adults With Renal Impairment
| Indications |
| 24 hours |
Hemodialysis Patients requiring hemodialysis should receive the recommended dose of Valacyclovir after hemodialysis. During hemodialysis, the half-life of acyclovir after administration of Valacyclovir is approximately 4 hours. About one-third of acyclovir in the body is removed by dialysis during a 4-hour hemodialysis session.
Peritoneal DialysisThere is no information specific to administration of Valacyclovir in patients receiving peritoneal dialysis. The effect of chronic ambulatory peritoneal dialysis and continuous arteriovenous hemofiltration/dialysis on acyclovir pharmacokinetics has been studied. The removal of acyclovir after CAPD and CAVHD is less pronounced than with hemodialysis, and the pharmacokinetic parameters closely resemble those observed in patients with end-stage renal disease not receiving hemodialysis. Therefore, supplemental doses of Valacyclovir should not be required following CAPD or CAVHD.
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Talk With Your Doctor If You’re Interested In Valacyclovir
Valacyclovir is a prescription medication, so you’ll need to consult with your health care provider to see if it’s the right drug for you. Be sure to let them know if you’re using any other medications or natural treatments for your herpes to avoid any unintended interactions.
Many natural treatments can be safely used in conjunction with valacyclovir. Low-level light therapy , for example, shines specific wavelengths of light onto herpes lesions in order to speed healing and ease inflammation. You can use a handheld red light therapy device like the Luminance RED Genital Treatment Device that makes this kind of proven treatment available in the privacy of your home.
How Long Does Valacyclovir Take To Work
The amount of time required for valacyclovir to control a herpes or chickenpox outbreak varies based on the severity of the outbreak and how soon you take valacyclovir after noticing herpes symptoms.
For most initial herpes outbreaks and cases of recurring herpes, valacyclovir takes effect very quickly and provides some level of relief in as little as two to three days. Generally, the sooner you take valacyclovir after noticing symptoms, the faster it will be to provide relief.
Its important to remember that every outbreak is different, meaning valacyclovir can potentially take less or more time than the figures listed above to provide relief and control over a shingles infection or herpes outbreak.
Our guide to how long valacyclovir takes to become effective covers more about valacyclovirs onset of action and average time to start working for different viral injections.
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How Much Valacyclovir Should You Take For A Cold Sore Outbreak
Cold sores also come and go, with many people experiencing recurrent outbreaks every few months after the initial outbreak passes. Like genital herpes, oral herpes outbreaks are often triggered by external factors, such as hormonal changes and illnesses.
The standard valacyclovir dosage for an outbreak of cold sores is the same as the dosage used for a primary oral herpes outbreak — 2,000 mg of valacyclovir taken every 12 hours, for a total of two doses. Taken early in a cold sore outbreak, this can significantly speed up healing.
For particularly bad outbreaks of cold sores, your doctor may also recommend the use of topical treatments, which can alleviate pain, itching and discomfort. Follow your doctors instructions on medication use for the fastest recovery and best results.
Valtrex Vs Zovirax : What’s The Difference
- Zovirax is also used to treat Epstein-Barr virus .
- Side effects of Valtrex and Zovirax that are similar include headache, nausea, vomiting, diarrhea, and rash.
- Side effects of Valtrex that are different from Zovirax include abdominal pain, cold symptoms, increased liver enzymes, reduced white blood cells, joint pain, and dizziness.
- Side effects of Zovirax that are different from Valtrex include agitation, confusion, anemia, muscle pain, hypersensitivity reactions, seizures, agitation, confusion, anemia, hepatitis, and muscle pain.
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What Conditions Do Acyclovir And Valacyclovir Treat
Acyclovir and valacyclovir are both used for the following indications:
- Treatment of chickenpox
Additionally, the acyclovir injection can be used to treat:
- Herpes of the brain in children and adults
- Herpes infection in newborn babies
Acyclovir and valacyclovir do not cure cold sores, herpes, or shingles. However, they relieve the symptoms of the outbreaks and help the lesions heal faster.
Does Valacyclovir Make You Gain Weight
Whilst valacyclovir can cause some side effects including headaches, abdominal pain and nausea, it isnt thought to cause weight gain. None of the studies or clinical trials of valacyclovir found weight gain as a side effect. There have been some anecdotal reports of valacyclovir causing weight gain but there are also anecdotal accounts of it causing weight loss. All of this is unverified and the weight changes could be coincidental. Talk to your doctor if youre concerned about any valacyclovir side effects.
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Overdose: What Happens If I Take Too Much Valtrex
If you take too much Valtrex, it can lead to acute kidney damage. This is a medical emergency that can cause toxicity in your body and the inability to make urine.
Hemodialysis is a procedure that helps your body eliminate toxins and balance fluidthis may be necessary until your kidney function is restored.
Clinical Trials Experience In Pediatric Subjects
The safety profile of Valacyclovir has been studied in 177 pediatric subjects aged 1 month to less than 18 years. Sixty-five of these pediatric subjects, aged 12 to less than 18 years, received oral tablets for 1 to 2 days for treatment of cold sores. The remaining 112 pediatric subjects, aged 1 month to less than 12 years, participated in 3 pharmacokinetic and safety trials and received Valacyclovir oral suspension. Fifty-one of these 112 pediatric subjects received oral suspension for 3 to 6 days. The frequency, intensity, and nature of clinical adverse reactions and laboratory abnormalities were similar to those seen in adults.Pediatric Subjects Aged 12 to Less than 18 Years In clinical trials for the treatment of cold sores, the adverse reactions reported by adolescent subjects receiving Valacyclovir 2 grams twice daily for 1 day, or Valacyclovir 2 grams twice daily for 1 day followed by 1 gram twice daily for 1 day , or placebo , respectively, included headache and nausea .Pediatric Subjects Aged 1 Month to Less than 12 YearsAdverse events reported in more than 1 subject across the 3 pharmacokinetic and safety trials in children aged 1 month to less than 12 years were diarrhea , pyrexia , dehydration , herpes simplex , and rhinorrhea . No clinically meaningful changes in laboratory values were observed.
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Can Valacyclovir Treat Shingles
Yes. Valacyclovir is an FDA-approved treatment for herpes zoster . It decreases the duration and severity of symptoms . It should be started as soon as possible after the rash starts. You will get the best response if you take the medication within 72 hours of the rash appearing .
Data shows that even if valacyclovir is started more than 72 hours after a rashs appearance, there can still be some benefit . Sometimes, depending on your pain level, your healthcare provider may recommend pain medication or over-the-counter remedies along with valacyclovir. As with other herpes viruses, valacyclovir does not cure shinglesit can make your current episode less painful and resolve faster if started right away.
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Valacyclovir Dosage For Genital Herpes
If you have genital herpes, youll understand how stressful an outbreak can be. People infected with genital herpes can experience four to five outbreaks of the virus per year, making it vital to have medication like valacyclovir on hand in the event you notice herpes lesions developing.
Like oral herpes, valacyclovir is highly effective at treating genital herpes and speeding up the healing process.
Genital herpes occurs in two phases. After being infected with the virus, most people will have an initial outbreak a powerful outbreak of the virus that can result in severe symptoms. After this, genital herpes presents itself in recurring outbreaks every few months.
The typical dose of valacyclovir used to treat an initial outbreak of genital herpes is 1,000 mg taken two times per day. This twice-daily 1,000 mg dosage usually continues over 10 days as the herpes outbreak retreats and the lesions close, scab and heal.
During a very severe initial outbreak of genital herpes, your doctor might recommend taking valacyclovir over a longer period.
For recurring genital herpes, the typical dosage of valacyclovir is 500 mg taken twice daily for three days.
As with cold sores, valacyclovir is most effective at treating genital herpes when its taken as early as possible during an outbreak. Taken early, consistently and at the right dose, use of valacyclovir can make dealing with a difficult genital herpes outbreak more manageable.
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Patients Materials And Methods
Subjects and setting. Healthy men and women who were seropositive for HSV-2 were considered for enrollment. Patients were eligible if they had a diagnosis of a first episode of genital HSV-2 infection 6 months before enrollment. Alternatively, patients were eligible if they had longstanding genital herpes infection and a recurrence rate of 6 episodes during the preceding year. Patients who had been receiving recent suppressive therapy were eligible if they reported 6 recurrences/year before initiating suppressive therapy. Suppressive therapy was stopped for at least 1 month before enrollment, and at least 1 recurrence was required during that time. Subjects were excluded if they were immunocompromised, HIV positive, had abnormal renal or hepatic function, or had a history of malabsorption or of ocular HSV. Women of childbearing potential had to use an effective method of contraception throughout the study. Study participants were recruited by newspaper advertisements, flyers, and local health clinics at 2 centers: the University of Washington Virology Research Clinic in Seattle and the Westover Heights Clinic in Portland, Oregon. Enrollment took place between August 1995 and July 1996. The protocol was approved by human subjects review committees, and all subjects gave written, informed consent.
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Rosanna Sutherby is a freelance medical writer who has been a practicing pharmacist in her community for close to 20 years. She obtained her Doctor of Pharmacy from Nova Southeastern University in Ft. Lauderdale, FL. She utilizes her clinical training in the pharmacy, where she helps patients manage disease states such as asthma, diabetes, heart disease, hypertension, and many others. Dr. Sutherby reviews and recommends drug regimens based on patients concurrent conditions and potential drug interactions.
References:
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When You Must Not Take Them
- Do not take Valtrex tablets if you have ever had an allergic reaction to valaciclovir, aciclovir or any of the ingredients listed at the end of this leaflet.
- Symptoms of an allergic reaction may be mild or severe. They usually include some or all of the following: wheezing, swelling of the lips/mouth, difficulty in breathing, hay fever, lumpy rash or fainting.
- Do not take Valtrex tablets if you are pregnant, trying to become pregnant or breast-feeding, unless your doctor says you should.
- Your doctor will discuss the risks and benefits of using Valtrex tablets when pregnant and during breast-feeding.
- Do not take Valtrex tablets after the expiry date printed on the pack.
- If you take it after the expiry date has passed, it may not work as well.
- Do not take Valtrex tablets if the packaging is torn or shows signs of tampering.
- If you are not sure whether you should be taking Valtrex, talk to your doctor.
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