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Valacyclovir
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DRUG INFO
Valacyclovir
Drug Name:
Valacyclovir
Indication: For the treatment or suppression of cold sores (herpes labialis), herpes zoster (shingles), genital herpes in immunocompetent individuals, and recurrent genital herpes in HIV-infected individuals.
Pharmacology: Valacyclovir is a prodrug and synthetic purine nucleoside analogue with inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV). Valacyclovir is almost completely converted to acyclovir and L-valine. The inhibitory activity of valacyclovir is highly selective due to its affinity for the enzyme thymidine kinase (TK) encoded by HSV and VZV. This viral enzyme converts acyclovir into acyclovir monophosphate, which is then converted into acyclovir diphosphate and triphosphate by cellular enzymes. Acyclovir is selectively converted to the active triphosphate form by cells infected with herpes viruses.
Mechanism Of Action: Valacyclovir is phosphorylated by viral thymidine kinase to acyclovir triphosphate (the active metabolite) which then inhibits herpes viral DNA replication by competitive inhibition of viral DNA polymerase, and by incorporation into and termination of the growing viral DNA chain. When used as a substrate for viral DNA polymerase, acyclovir triphosphate competitively inhibits dATP leading to the formation of 'faulty' DNA. This is where acyclovir triphosphate is incorporated into the DNA strand replacing many of the adenosine bases. This results in the prevention of DNA synthesis, as phosphodiester bridges can longer to be built, destabilizing the strand.
Drug Category: Prodrugs; Antivirals; ATC:J05AB
Brand Names/Synonyms: Acyclovir; BW 256U87; Valaciclovir; Valaciclovir Hcl; Valaciclovir Hydrochloride; Valacyclover Hydrochloric; Valacyclover Hydrochloride; Valacyclovir; Valacyclovir Hydrochloride; Valtrex; Zovirax
Dosage Forms: TABLET
Absorption: After oral administration, valacyclovir hydrochloride is rapidly absorbed from the gastrointestinal tract. The absolute bioavailability of acyclovir after administration of valacyclovir is 54.5% ± 9.1%.
Interactions: Interactions for Valacyclovir:
The pharmacokinetics of digoxin was not affected by coadministration of Valacyclovir 1 gram 3 times daily, and the pharmacokinetics of acyclovir after a single dose of Valacyclovir (1 gram) was unchanged by coadministration of digoxin (2 doses of 0.75 mg), single doses of antacids (Al3+ or Mg++), or multiple doses of thiazide diuretics. Acyclovir Cmax and AUC following a single dose of Valacyclovir (1 gram) increased by 8% and 32%, respectively, after a single dose of cimetidine (800 mg), or by 22% and 49%, respectively, after probenecid (1 gram), or by 30% and 78%, respectively, after a combination of cimetidine and probenecid, primarily due to a reduction in renal clearance of acyclovir. These effects are not considered to be of clinical significance in subjects with normal renal function. Therefore, no dosage adjustment is recommended when Valacyclovir is coadministered with digoxin, antacids, thiazide diuretics, cimetidine, or probenecid in subjects with normal renal function.
Chemical IUPAC Name: 2-[(2-amino-6-oxo-3,9-dihydropurin-9-yl)methoxy]ethyl2-amino-3-methyl-butanoate
Chemical Formula: C13H20N6O4
Half Life: 2.5-3.3 hours
Drug Type: Approved Drug
# Accession No: APRD00697
CAS Registry Number: 124832-27-5
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Valacyclovir News
(When available)
Pharma cos may record modest growth in Q3 16 Jan 2006
TMCnet ...currently in litigation. The rulings for Actos, Valtrex, Fiomax, Provigil and Tricor are expected in the coming months. Dr Reddy's ...
Pharma cos may record modest growth in Q3 Jan 15, 2006
Economic Times, 7-8 are currently in litigation. The rulings for Actos, Valtrex, Fiomax, Provigil and Tricor are expected in the coming months.
'Kissing disease' responds to newer form of old drug Jan 12, 2006
Macleans, ...of Minnesota, decided to take another look at the treatment, this time in the form of a related medication called valacyclovir (brand name Valtrex), which is ...
1/13 WWE Friday Night Smackdown Express: New champion, other new ... Jan 14, 2006
Pro Wrestling Torch Piper said it looked like some sort of herpes, and said that they have Valtrex which can bring that down. JBL had to hold Jillian back. ...
Herpes virus can go into hiding Dec 19, 2005
Charleston Post Courier (subscription), Several medications - acyclovir (Zovirax, generic), famciclovir (Famvir) and valacyclovir (Valtrex) - can shorten a herpes outbreak by a day or two. ...
Indian drug firms to continue with strategy Dec 19, 2005
International Herald Tribune, Besides Lipitor, Ranbaxy is fighting more than a half-dozen cases challenging patents on brands like GlaxoSmithKline's herpes drug Valtrex; AstraZeneca's anti ...
Indian Drug Maker Says It Will Keep Attacking Patents Despite ... Dec 19, 2005
New York Times, In addition to Lipitor, Ranbaxy is fighting more than a half-dozen cases challenging the patents on brands like Valtrex, GlaxoSmithKline's herpes drug; Nexium ...
Herpes virus can go into hiding Dec 19, 2005
Charleston Post Courier (subscription), Several medications - acyclovir (Zovirax, generic), famciclovir (Famvir) and valacyclovir (Valtrex) - can shorten a herpes outbreak by a day or two. ...
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