Valacyclovir
Risk Factor: BM
Class: Anti-infectives
/ Antivirals
Contents of this page:
Fetal Risk Summary
Valacyclovir is biotransformed to acyclovir and L-valine by first-pass intestinal and/or hepatic metabolism. The drug is active against herpes simplex virus types 1 and 2 and varicella-zoster virus. It is used in the treatment of herpes zoster (shingles) and recurrent genital herpes simplex.
Reproduction studies were conducted in rats and rabbits during organogenesis with doses of 400 mg/kg, producing concentrations 10 and 7 times human plasma levels, respectively (1). No teratogenic effects were observed with these doses.
The active metabolite, acyclovir, readily crosses the human placenta (see Acyclovir). An abstract and study, both published in 1998, compared the pharmacokinetics of valacyclovir and acyclovir in late pregnancy (2,3). Acyclovir accumulated in the amniotic fluid but not in the fetus. The mean maternal/umbilical vein plasma ratio at delivery was 1.7.
The Valacyclovir Pregnancy Registry listed 157 prospective reports of women exposed to the oral antiviral drug during gestation covering the period from January 1, 1995, through April 30, 1999 (4). Of the total, 47 (30%) pregnancies were lost to follow-up. Among the 111 (1 set of twins) known outcomes, 29 had earliest exposure in the 1st trimester and their outcomes were 5 spontaneous abortions, 2 induced abortions, 1 infant with a birth defect (talipes), and 21 infants (including the twins) without birth defects. When the earliest exposure was in the 2nd trimester, 31 pregnancies were enrolled and their outcomes were 2 stillbirths, 2 infants with birth defects (fingers and toes fusedextensive webbing; small cleft in front gum), and 27 without birth defects. In the remaining 51, the earliest exposure occurred in the 3rd trimester, with 1 infant with a dermal sinus tract and 50 without birth defects (4).
A total of 34 retrospective reports of valacyclovir exposure during pregnancy were submitted to the Registry (4). Two of the exposures occurred during an unspecified gestational time and both resulted in live births without defects. In 14 pregnancies, the earliest exposure occurred during the 1st trimester. The outcomes of these pregnancies were three spontaneous losses, eight induced abortions, and three infants without birth defects. For the pregnancies whose earliest exposure was in the 2nd trimester (N=4) or 3rd trimester (N=14), there was 1 birth defect (2nd trimester exposure) and 17 infants without defects. (See the statement below that is required by the registry for use of these data.) A 1999 case report described a woman at 20 weeks' gestation who had a generalized herpes simplex virus infection that was treated with IV acyclovir for about 2 weeks followed by valacyclovir for the remainder of the pregnancy (5). She delivered a full-term, healthy female infant who was treated prophylactically with oral acyclovir for 1 month. No abnormalities were detected during a neurologic examination at 8 months of age.
Except for the above data, no other reports describing the use of valacyclovir during human pregnancy have been located. However, a large number of studies have reported the use of the active metabolite, acyclovir, during human pregnancy (see also Acyclovir). Based on the combined data, there does not appear to be any major risk to the human fetus from valacyclovir or acyclovir. Long-term follow-up of children exposed in utero to these agents is warranted.
Required statement: The cases accumulated represent a sample of insufficient size for reaching reliable and definitive conclusions regarding the risk of valacyclovir to pregnant women and developing fetuses. In addition, underreporting, differential reporting, and losses to follow-up are potential limitations of the registry. Despite these limitations, the registry was intended to supplement animal toxicology studies and assist clinicians in weighing the risks and benefits of treatment for individual patients and circumstances.
Breast Feeding Summary
No reports have been located that described the use of valacyclovir during human lactation. Valacyclovir is rapidly and nearly completely converted to acyclovir and the amino acid, L-valine. Acyclovir is concentrated in human milk with milk:plasma ratios in the 34 range (see Acyclovir). Because acyclovir has been used to treat herpesvirus infections in the neonate, and because of the lack of adverse effects in reported cases in which acyclovir was used during breast feeding, the American Academy of Pediatrics considers acyclovir to be compatible with breast feeding (see Acyclovir) (6). Based on this information, valacyclovir should also be compatible with breast feeding.
References
- Product information. Valtrex. Glaxo Wellcome, 1997.
- Kimberlin DF, Weller S, Andrews WW, Hauth JC, Whitley RJ, Lakeman F, Miller G, Lee C, Goldenberg RL. Valaciclovir pharmacokinetics in late pregnancy (abstract). Am J Obstet Gynecol 1998;178:S12.
- Kimberlin DF, Weller S, Whitley RJ, Andrews WW, Hauth JC, Lakeman F, Miller G. Pharmacokinetics of oral valacyclovir and acyclovir in late pregnancy. Am J Obstet Gynecol 1998;179:84651.
- Acyclovir Pregnancy Registry and Valacyclovir Pregnancy Registry. Final study report. 1 June 1984 through 30 April 1999. Glaxo Wellcome, 1999.
- Anderson R, Lundqvist A, Bergstrom T. Successful treatment of generalized primary herpes simplex type 2 infection during pregnancy. Scand J Infect Dis 1999;31:2012.
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Committee on Drugs. American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:13750.
Questions and Answers
will giving antiviral agent like valacyclovir later than 72 hours upon start of herpes zoster still effective?,
It may, and it may not.
Valacyclovir, for herpes zoster, should actually be taken within 48 hours of the onset of a rash to be most effective, though the clinical studies performed started treatment within 72 hours (*info on the package insert)
I would like to know the mode of actions of Acyclovir and Valacyclovir on the DNA viruses?,
Acyclovir and valacyclovir are homologues of DNA nucleotides. There is a particular enzyme encoded by HSV and VZV which begins a cascade of biochemical reactions that allows the drug to be inserted in a growing DNA chain in place of the natural nucleotide. The chemical structure of the drug is such that once it becomes incorporated into the DNA, no further bases can be added to the DNA and the replication must stop. As a result of this, cells infected by the virus cannot replicate and will die, while the uninfected cells will (ideally) be left along by the drug.
how dose valacyclovir (valtrex) work?, what dose it distribute into the body to help with out breaks?
It gets converted by the liver to a molecule that is is very similar to a nucleotide, which then gets distributed though out the body, and then incorporated into DNA. The virus puts it in its DNA, but since it's not a perfect fit, it gums up the mechanism, and the virus DNA can't grow anymore. It's not so much of a problem for your own DNA, so it can help reduce the virus without killng you.
What is the best cold sore medication?, The ones I've heard of are Acyclovir, Famciclovir, and Valacyclovir.
i know i get coldsores from the sun and i want to take a daily medication for them. i only get 2-3 outbreaks a year and theyre always in the summer.
also are there any other ways to prevent coldsores? ive heard sunscreen on the lips helps.and suggestions?
thanks in advance.
Abreva works best for me .. use a lip balm with UV protection during the summer months
I am taking medicines for my herpes outbreaks but they dont seem to have any effect. What should I do?, I am taking valacyclovir HCL (valtrex) but the herpes sores seems to be re-appearing. Is it my imagination?
No.Your meds need to be changed
Does taking herpes medication cause erectile dysfunction?, I am taking herpes medication (Valacyclovir 500 mg) for the past several weeks. I suspect it is causing erectile dysfunction to me as I have observed on myself now. Is it true or is my E.D due to some other reason. I am 43 y.o and Divorced.
NO! Valtrex is an excellent drug for HSV. You are stressing about it all too much. Have look at www. herpes-info-center.com to get decent info.
Valtrex(Valacyclovir ) question?, I have got severe cold sore in mouth like ever other week, my doctor prescribed me valtrex 1 G, ( 2 Gm once , twice a day) and it worked it is gone with in a day and it never occured liek for one month now again the same routine got sore mouth liek ever other week and it stays for almost 2-3 weeks , I I have this problem from like 15 years and looks like ther eis no cure for it.
- now shall I tale one valtrex daily ? or when ever cold sore break I shall take it, it is very expensive medicene and when I take it I got conctipation as well.
do any one know how much valtrex cost in India so I can get it in bulk from there ?
is it ok to take valtrex for my problem?
There is no cure for herpes simplex 1. But if you take the valtrex daily it will reduce your number of break outs. Alot of breakouts happen when you get stressed out. So try and eliminate as much stress as possible. Get lots of sleep too. If you take your valtrex daily and not miss, your breakouts will be reduced for sure. Hopefully you will find a way to get it cheaper. Good luck...
I am looking for a lubricant or foam that offers some degree of protection against Herpes Simplex Virus?, My girlfriend has Genital Herpes HSV-I, but rarely has outbreaks. We are going to use Valacyclovir as a prophylaxis and of course a condom; however, I would like to have an antiviral gel or foam to cover the areas not covered by the condom. You guys have any recommendations?
Gel provides protection from HIV and herpes
http://www.news-medical.net/?id=7980
"Mount Sinai School of Medicine researchers demonstrated that a gel applied in the vagina provides protection from both the human immunodeficiency virus (HIV) and the herpes simplex Virus. The study, presented at the 12th Conference on Retroviruses and Opportunistic Infections, is the first to show that a gel can retain anti-viral activity within the human vagina"
Can you find the cheapest available online? 10 points for best answer!!?, Valacyclovir 21 1000mg tablets for shingles. Please could you tell me the cost of these including shipping. thankyou. Also they must ship to the UK.
Don't buy medicines online as in most cases you'd be getting counterfeits. You'd be paying money to get talc, flour, dust etc .... I know valcyclovir are expensive buy you should get them from your local pharmacy.
cold sores - care for an opinion?, I've read a lot of nonsense online about how to treat a cold sore, and I figured I'd record my position on the issue.
My cold sores, and those of many people, are introduced by (1) an odd redness that stands out from the rest of the lip, (2) the appearance of tiny little bumps which increase in size and number, (3) the concurrent swelling of those regions, and (4) (prior to any visible bumps) the feeling that the redness is colder than the rest of the lip.
I 've had my share of cold sores: the first one lasted two weeks, the second lasted one week because I handled it better, and all subsequent ones have lasted no more than 36 hours before the sore receded but I'll say 2-3 days to be safe.
At the first sign of a sore, I take an antiviral drug. I do not wish to advertise, but there are only three major drugs out there: acyclovir, valacyclovir (valtrex), and then there's Famvir. I can only talk of valacyclovir - it works by blocking the action of enzyme DNA Polymerase, without which the virus can't replicate. Valacyclovir has greater bioavailability, which means more of the drug can be used by your body (55% vs 15%).
After taking my medication, the little bumps keep increasing in size and number, and it has been my perception that the drug initially speeds up this process.You keep looking in the mirror, only to see the blisters form what appear to be continental masses divided by many canals - they haven't merged yet. The development of the sore after taking the drug peaks 12-16 hours later, and meanwhile you wonder how bad your scar will be. At the 24 hour mark, you relax because it becomes clear the sore has stopped growing, and at 30 hours, the sore has begun receding. One day and a half, the skin where the breakout occurred was only slight darker than the surrounding skin, but it was not broken or breached, and it's a matter of a little more time for it to look like the surrounding skin. Not a bad feat considering it had been populated by many white blisters so close together they looked like they HAD to scab in order to heal.
All over the internet I have found tips to speed the drying and scabbing process. But this seems like *utter nonsense*. If you take your drug at first symptoms (and you learn to recognize those), the blisters will continue to progress, but will then *recede*. Now, if the skin is still strong and healthy, it will recover, without any scabbing and hence without any scarring. My worst blisters in the past 2 years have completely receded within 36 hours, without a scab and without a scar. Throughout the breakout I made sure to apply a good lip moisturizer frequently (but using good common sense to never actually touch the sore itself, or wash my hands very thoroughly before touching other parts of my body), to prevent the skin around a blister from drying and beginning to scab.
A browse through the internet will show many alarming pictures than should be rated R, and show you many horrific scenarios - all of which seem to do nothing but stress you out. The fact is this: if you take your drug at *first symptoms*, and keep the skin strong with a good moisturizer without biting at it, you should be fine.
ABREVA!!!
