Vaclovir (Valaciclovir) 500mg

Vaclovir general information

What is Vaclovir used for?

Vaclovir tablets 500mg are used to treat infections of the skin and mucous membranes caused by Herpes Simplex Virus (HSV), including cold sores (herpes labialis); also initial and recurrent episodes of genital herpes in people with a healthy immune system, and can prevent lesions when taken as soon as symptoms of an HSV recurrence appears.  Vaclovir tablets 500mg are also used for suppression of recurrent genital herpes infections in people with an active immune system (immunocompetent) and to reduce the transmission of genital herpes to others.  In HIV-infected patients who are immunocompromised, Vaclovir tablets 500mg are used for prevention (prophylaxis) of herpes infections.  Vaclovir tablets 500mg are also used to treat cold sores in children who are at least 12 years old, and to treat chickenpox, caused by the closely related Varicella Zoster Virus (VZV) in children who are at least 2 years old.  Vaclovir tablets 500mg are also used to treat Herpes zoster (shingles) caused by VZV in immunocompetent adults, provided the infection is less than 72 hours duration.  Vaclovir tablets 500mg are also used to prevent opportunistic infection with cytomegalovirus (CMV) and other herpes virus infections (HSV, VZV) following organ transplantation

How does Vaclovir work?

Vaclovir tablets 500mg contain valacyclovir, a prodrug of acyclovir that is more readily absorbed and is converted to acyclovir by the liver.  Valacyclovir in Vaclovir tablets 500mg then works in the same way as acyclovir, as an antiviral agent that is highly active against both types of herpes simplex virus, HSV-I, that causes cold sores and HSV-II that causes genital herpes; and also against the closely related varicella zoster herpes virus that causes chicken pox and shingles.  Acyclovir inhibits the action of a viral enzyme (DNA polymerase), blocking viral DNA synthesis without affecting normal cellular processes.  This prevents the virus replicating and therefore, stops the growth and spread of the virus, relieving symptoms of the infection and helping the body to fight off the infection.  Vaclovir tablets 500mg will not cure a herpes infection, as the virus can lie dormant in infected cells until reactivated when immunity is low due to stress or other illness or even exposure to sunlight, causing new infections like cold sores and shingles; but it does reduce pain and help the sores caused by the infection to heal faster.

What does Vaclovir contain?

Vaclovir tablets 500mg contains the active ingredient valacyclovir 500mg, an antiviral used to treat herpes virus infections.  They also contain microcrystalline cellulose and magnesium stearate in the tablet core and hypromellose, titanium dioxide and polyethylene glycol in the film coat.

Treating herpes infection with Vaclovir

Vaclovir tablets 500mg contain valacyclovir, an antiviral agent which is highly active against both types of herpes simplex virus, HSV-I, that causes cold sores and HSV-II that causes genital herpes and also against the closely related varicella zoster herpes virus that causes chicken pox and shingles.  HSV Infections are characterised by blisters which form in the mucous membranes of the mouth, lips or genitals and crust over to form a scab as they heal.  Vaclovir tablets 500mg stop the virus in infected cells from being able to replicate and spread, helping to relieve symptoms and heal the blisters. 

Treating shingles with Vaclovir-500

Vaclovir tablets 500mg contain valacyclovir, an antiviral agent which is highly active against both types of herpes simplex virus, HSV-I, that causes cold sores and HSV-II that causes genital herpes and also against the closely related varicella zoster herpes virus that causes chicken pox and shingles.  Herpes zoster or shingles is caused by the same type of herpes virus that causes the common childhood infection chicken pox (varicella).  The blisters associated with chicken pox are characteristic of the initial infection with varicella zoster virus (of the herpes family) which migrate to nerve cells and remain dormant (not replicating) once chicken pox blisters have gone.  Years later, the virus can be activated by stress, other illness or even exposure to sunlight, causing the virus to travel down the nerve and infect the skin again, replicating and causing the painful rash of blisters associated with shingles as well as nerve pain or post-herpetic neuralgia.  Vaclovir tablets 500mg can help reduce the duration and severity of acute symptoms and rash as well as reduce zoster-associated pain.  

Vaclovir for genital herpes

Vaclovir tablets 500mg contain valacyclovir, an antiviral agent which is highly active against both types of herpes simplex virus, HSV-I, that causes cold sores and HSV-II that causes genital herpes, although HSV-I can also cause genital herpes, which is a sexually transmitted disease characterised by painful sores and blisters around the genital areas.  Genital herpes can recur several times, particularly if your immune system is low or compromised.  Vaclovir tablets 500mg can be used to treat an initial infection of genital herpes and reduce painful symptoms; and is also used for suppression to prevent the infection recurring.

What are the side effects of Vaclovir?

The most commonly reported side effects when taking Vaclovir tablets 500mg include headache, nausea, photosensitivity.

When should Vaclovir not be used?

You should not use Vaclovir tablets 500mg if you:

• are allergic to valacyclovir or any ingredients in Vaclovir
• are pregnant or are breastfeeding
• have kidney or liver disease
• have had a bone marrow transplant
• are taking medicines that interact with Vaclovir-500, without discussion with your doctor, including probenecid (a treatment for gout), cimetidine for ulcers, methotrexate for cancer treatment, the immunosuppressant ciclosporin, the antiviral foscarnet, aminoglycoside antibiotics.

What medications interact with Vaclovir?

Several medications interact with Vaclovir and should either not be taken while you are taking Vaclovir or only after discussion and instruction from your doctor:

• Drugs that affect Vaclovir: probenecid (a treatment for gout), cimetidine for ulcers, methotrexate for cancer treatment, the immunosuppressant ciclosporin, the antiviral foscarnet, aminoglycoside antibiotics

How should Vaclovir be taken?

You should take your Vaclovir tablets 500mg swallowed whole with a glass of water with or without food, once, twice or three times daily depending on what you are being treated for and your doctor’s recommendations.  You should start taking your Vaclovir tablets 500mg as soon as possible after the first appearance of symptoms, such as tingling, burning, blisters.  The dose you take, how often and for how long depends on what you are being treated for and your doctors recommendations.  Your course of treatment may last for 3 to 10 days for an initial infection or longer, depending on your condition and whether you are taking Vaclovir tablets 500mg for initial or recurrent infection or for prevention. 

How long should you take Vaclovir?

You should continue to take your Vaclovir-500 for as long as recommended by your doctor, which may be for 3-10 day, or longer depending on your condition and what you are being treated for.

Missed dose of Vaclovir

If you miss a dose of Vaclovir tablets 500mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Vaclovir be stored?

You should store your Vaclovir tablets 500mg below 25°C in a cool dry place.