 |
 |
|
|
Antiviral Medications to Treat and Prevent HerpesHerpes is an infection caused by herpes simplex virus. Herpes is caused by two viruses: herpes simplex virus type 1 (HSV-1), and herpes simplex virus type 2 (HSV-2). HSV-1, the virus responsible for common cold sores, can be transmitted through oral secretions. HSV-2 causes the majority of genital herpes cases and can be transmitted through oral or genital secretions. Research shows that 90% of the population has been exposed to HSV-1 and 25% of the population aged 25-45 years old in the United States has been exposed to infection with HSV-2. Cold sores (also called fever blisters) are quite different from canker sores, a condition people sometimes associate them with. Cold sores are caused by the herpes simplex virus, and they're contagious. You can't cure or prevent cold sores, but you can take steps to reduce their frequency and to limit the duration of an occurrence. If you experience frequent bouts, your doctor may prescribe an antiviral medication to treat cold sores. Genital herpes is a highly contagious sexually transmitted disease. The cause is a strain of the herpes simplex virus. This virus enters your body through small breaks in your skin or mucous membranes. The illness is characterized by pain, itching and sores in your genital area. There's no cure for genital herpes. However, oral prescription antiviral medications, including acyclovir (Zovirax), famciclovir (Famvir) and valacyclovir (Valtrex), can help heal the sores sooner and reduce the frequency of relapses. If taken daily, these medications may also reduce the chance you'll infect your partner with the herpes virus. Antiviral medications are used to prevent or treat herpes infections, they stop the growth of the herpes simplex virus. Antiviral medications may significantly lessen the severity of a primary outbreak and reduce the time it takes genital herpes outbreaks to heal. The medication also decreases the number of days of painful symptoms and for some people, the number of days you can spread the virus. Currently, there is no cure for herpes. However, there are three antiviral medications approved by the Food and Drug Administration (FDA) for the treatment of herpes: Zovirax® (acyclovir), Famvir® (famciclovir), and Valtrex® (valacyclovir). In the US antiviral medications are only available by prescription. The drugs differ in their chemical structure, how often you take them, price and FDA licensed indications. (Yuo should know that not every area where a drug is effective receives an FDA indication.) How do antiviral medications work? All three drugs disrupt the process by which the virus makes copies of itself and spreads to new cells. They do this by inhibiting an enzyme that the virus has but human cells do not and then interrupting the viruses' ability to synthesize DNA. None of the therapies cures the viral infection. HSV-1 and HSV-2 will remain dormant in the body in the nerve ganglia. Effectiveness of antiviral medications
The effectiveness of the acyclovir (Zovirax), famciclovir (Famvir), and valacyclovir (Valtrex) are equal in studies done so far. Why antiviral medications are used
Acyclovir (Zovirax®) Acyclovir was the first successful drug for genital herpes and was originally licensed in the early 1980s for the treatment and suppression of genital herpes. It is sold under the brand name Zovirax® but is now available as a generic from many manufacturers and is by far the cheapest of the available antivirals. Acyclovir is a safe and extremely well-tolerated drug. The Acyclovir in Pregnancy Registry has documented prenatal exposures in more than 850 women (with 578 first-trimester exposures) without any adverse outcomes. However, the total number of pregnancies monitored to-date may not be enough to detect defects that occur only infrequently. The topical form of acyclovir (Zovirax ointment) offers little benefit in the treatment of genital herpes and is not recommended. Valaciclovir (Valtrex®) Valacyclovir, a new antiviral agent. Valacyclovir is a prodrug converted to acyclovir in the intestine and liver. It has an oral bioavailability three to five times greater than that of acyclovir. Some people have called it intravenous acyclovir in pill form. The better absorption allows less frequent dosing. Valacyclovir has the advantage of once-daily dosing. Valtrex, when taken daily (suppressive therapy) by a person with recurrent genital herpes, can reduce the risk of transmission to a partner. Famciclovir (Famvir®) Famciclovir, another new antiviral medication, is the oral form of penciclovir, a purine analog similar to acyclovir. The drug is quickly converted to its active form. Mechanism and efficacy are similar to those of acyclovir. Famciclovir has also been shown to be effective for both episodic and suppressive therapy of genital herpes. Difference dosages are used for different treatment goals. Famciclovir, despite its favorable intracellular pharmacokinetics, must be given twice daily to be effective. Safety Issues A large volume of research suggests that the medications are safe and have few or no side effects. These medications have never been noted to cause any long-term side effects. All three antivirals mentioned earlier are Pregnancy Category B. All these drugs can have renal toxicity, and their dosage schedules must be reduced in patients with renal failure.
Interesting Facts
|
