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ValaciclovirSystematic (IUPAC) name2-ethyl (2R)-2-amino-3-methylbutanoateIdentifiersCAS number124832-26-4ATC codeJ05AB11PubChem60773DrugBankAPRD00697ChemSpider54770Chemical dataFormulaC13H20N6O4 Mol. mass324.336 g/molSMILESeMolecules & PubChemPharmacokinetic dataBioavailability55%Protein binding13–18%MetabolismHepatic (to aciclovir)Half life<30 minutes (valaciclovir);2.5-3.6 hours (aciclovir)ExcretionRenal 40–50% (aciclovir),faecal 47% (aciclovir)Therapeutic considerationsPregnancy cat.B3 (Au), B (U.S.)Legal statusS4 (Au), POM (UK), ℞-only (U.S.)RoutesOralValaciclovir (INN) or valacyclovir (USAN) is an antiviral drug used in the management of herpes simplex and herpes zoster (shingles). It is a prodrug, being converted in vivo to aciclovir. It is marketed by GlaxoSmithKline under the trade name Valtrex or Zelitrex.// Pharmacology Mechanism of actionValaciclovir is a prodrug, an esterified version of aciclovir that has greater oral bioavailability (about 55%) than aciclovir (10-20%). It is converted by esterases to the active drug aciclovir via hepatic first-pass metabolism. Acyclovir is selectively converted into a monophosphate form by viral thymidine kinase, which is far more effective (3000 times) in phosphorylation than cellular thymidine kinase. Subsequently, the monophosphate form is further phosphorylated into the active triphosphate form, aciclo-GTP, by cellular kinases. Aciclo-GTP is a very potent inhibitor of viral DNA polymerase; it has approximately 100 times higher affinity to viral than cellular polymerase. Its monophosphate form also incorporates into the viral DNA, resulting in chain termination. It has also been shown that the viral enzymes cannot remove aciclo-GMP from the chain, which results in inhibition of further activity of DNA polymerase. Aciclo-GTP is fairly rapidly metabolised within the cell, possibly by cellular phosphatases. MicrobiologyAciclovir, the active metabolite of valaciclovir, is active against most species in the herpesvirus family. In descending order of activity:Herpes simplex virus type I (HSV-1)Herpes simplex virus type II (HSV-2)Varicella zoster virus (VZV)Epstein-Barr virus (EBV)Cytomegalovirus (CMV)Activity is predominantly active against HSV, and to a lesser extent VZV. It is only of limited efficacy against EBV and CMV, however, valacyclovir has recently been shown to lower or eliminate the presence of the Epstein-Barr virus in subjects afflicted with acute mononucleosis, leading to a significant decrease in the severity of symptoms. It is inactive against latent viruses in nerve ganglia.To date, resistance to valaciclovir has not been clinically significant. Mechanisms of resistance in HSV include deficient viral thymidine kinase; and mutations to viral thymidine kinase and/or DNA polymerase, altering substrate sensitivity. IngredientsValtrex is offered in 500mg and 1gram tablets, the active ingredient being valacyclovir hydrochloride, with the inactive ingredients carnauba wax, colloidal silicon dioxide, crospovidone, FD&C Blue No. 2 Lake, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, povidone, and titanium dioxide. Clinical use IndicationsValaciclovir is indicated for the treatment of HSV and VZV infections, including:Genital herpes simplex (treatment and prophylaxis)Reduction of HSV transmission from people with recurrent infection to uninfected individualsHerpes zoster (shingles)Prevention of CMV disease following organ transplantationIt has shown promise as a treatment for infectious mononucleosis and is preventatively administered in suspected cases of Herpes B Virus exposure. Adverse effectsCommon adverse drug reactions (≥1% of patients) associated with valaciclovir therapy are the same as for aciclovir, its active metabolite, and include: nausea, vomiting, diarrhea, anal leakage and/or headache. Infrequent adverse effects (0.1–1% of patients) include: agitation, vertigo, confusion, dizziness, edema, arthralgia, sore throat, constipation, abdominal pain, rash, weakness and/or renal impairment. Rare adverse effects (<0.1% of patients) include: coma, seizures, neutropenia, leukopenia, tremor, ataxia, encephalopathy, psychotic symptoms, crystalluria, anorexia, fatigue, hepatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis and/or anaphylaxis.Valaciclovir is contraindicated in immuno-suppressed patients such as those infected with HIV as it may cause thrombotic thrombocytopenic purpura and hemolytic uremic syndromes resulting in kidney failure. Aciclovir is preferred in these patients.Valaciclovir was recently approved for generic production. Teva, Mylan, Ranbaxy (an Indian company) will all have the generic versions on the market by the end of 2009 or sooner.
L: Quote, Profile, Research). health regulators for its generic version of GlaxoSmithKline Plc's (GSK. Now what is Valtrex? If you donât know then you must not have used it; good for you!. And⦠If you are at all familiar with target marketing, you understand that those advertisements are not just there for us non-herpes having individuals to giggle. And sadly, it would be a lie I blindly accepted.The major drugs developed to work against herpes simplex virus (HSV) are antiviral agents called nucleosides and nucleotide analogues, which block viral reproduction. Actually, youâve probably seen a lot of them â theyâre on all of the time lately. This week really challenged Bret's blondetourage. Little did I know, that was just yet another lie disseminated by the public school system, along with other whoppers such as Columbus discovering America and the entire subject of Algebra. One in four New Yorkers is spreading the gift that keeps on giving around the Big Apple.Will you stay and rock my world?Bret Michaels is a lucky man.. Oct 5 (Reuters) - Israel's Teva Pharmaceutical Industries Ltd (TEVA.GlaxoSmithKline plans to close Dartford, UK manufacturing plant, cutting 620 more jobs by 2013. The cuts come as CEO Andrew Witty attempts to improve
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