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valacyclovir hydrochloride
Overview
What is VALTREX?
VALTREX (valacyclovir hydrochloride) is the hydrochloride salt of the ─valyl ester of the antiviral drug acyclovir.
VALTREX Caplets are for oral administration. Each caplet contains valacyclovir hydrochloride equivalent to 500 mg or 1 gram valacyclovir and 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. The blue, film─coated caplets are printed with edible white ink.
The chemical name of valacyclovir hydrochloride is -valine, 2-[(2-amino-1,6-dihydro-6-oxo-9-purin-9-yl)methoxy]ethyl ester, monohydrochloride. It has the following structural formula:
Valacyclovir hydrochloride is a white to off─white powder with the molecular formula CHNO•HCl and a molecular weight of 360.80. The maximum solubility in water at 25°C is 174 mg/mL. The pks for valacyclovir hydrochloride are 1.90, 7.47, and 9.43.
What does VALTREX look like?
What are the available doses of VALTREX?
Caplets: 500 mg (unscored), 1 gram (partially scored) ()
What should I talk to my health care provider before I take VALTREX?
How should I use VALTREX?
Cold Sores (Herpes Labialis):
Genital Herpes:
Initial Episode:
Recurrent Episodes:
Suppressive Therapy:
Reduction of Transmission:
Sexually Transmitted Diseases Treatment Guidelines
Herpes Zoster:
Cold Sores (Herpes Labialis):
Genital Herpes:
Initial Episode:
Recurrent Episodes:
Suppressive Therapy:
In HIV─1─infected patients with a CD4+ cell count greater than or equal to 100 cells/mm, the recommended dosage of VALTREX for chronic suppressive therapy of recurrent genital herpes is 500 mg twice daily.
Reduction of Transmission:
Herpes Zoster:
What interacts with VALTREX?
Sorry No Records found
What are the warnings of VALTREX?
Sorry No Records found
What are the precautions of VALTREX?
Sorry No Records found
What are the side effects of VALTREX?
Sorry No records found
What should I look out for while using VALTREX?
VALTREX is contraindicated in patients who have had a demonstrated clinically significant hypersensitivity reaction (e.g., anaphylaxis) to valacyclovir, acyclovir, or any component of the formulation .
What might happen if I take too much VALTREX?
Caution should be exercised to prevent inadvertent overdose . Precipitation of acyclovir in renal tubules may occur when the solubility (2.5 mg/mL) is exceeded in the intratubular fluid. In the event of acute renal failure and anuria, the patient may benefit from hemodialysis until renal function is restored .
How should I store and handle VALTREX?
Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].Product: 63629-3610NDC: 63629-3610-1 1 TABLET, FILM COATED in a BOTTLEProduct: 63629-3610NDC: 63629-3610-1 1 TABLET, FILM COATED in a BOTTLE
Clinical Information
Chemical Structure
No Image foundClinical Pharmacology
Valacyclovir is an antiviral drug
Non-Clinical Toxicology
VALTREX is contraindicated in patients who have had a demonstrated clinically significant hypersensitivity reaction (e.g., anaphylaxis) to valacyclovir, acyclovir, or any component of the formulation .Topiramate
Some patients may experience a large increase in amitriptyline concentration in the presence of topiramate and any adjustments in amitriptyline dose should be made according to the patient's clinical response and not on the basis of plasma levels.
Drugs Metabolized by P450 2D6
The biochemical activity of the drug metabolizing isozyme cytochrome P450 2D6 (debrisoquin hydroxylase) is reduced in a subset of the caucasian population (about 7 to 10% of Caucasians are so called “poor metabolizers”); reliable estimates of the prevalence of reduced P450 2D6 isozyme activity among Asian, African and other populations are not yet available. Poor metabolizers have higher than expected plasma concentrations of tricyclic antidepressants (TCAs) when given usual doses. Depending on the fraction of drug metabolized by P450 2D6, the increase in plasma concentration may be small, or quite large (8 fold increase in plasma AUC of the TCA).
In addition, certain drugs inhibit the activity of this isozyme and make normal metabolizers resemble poor metabolizers. An individual who is stable on a given dose of TCA may become abruptly toxic when given one of these inhibiting drugs as concomitant therapy. The drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide). While all the selective serotonin reuptake inhibitors (SSRIs), e.g., fluoxetine, sertraline, and paroxetine, inhibit P450 2D6, they may vary in the extent of inhibition. The extent to which SSRI-TCA interactions may pose clinical problems will depend on the degree of inhibition and the pharmacokinetics of the SSRI involved. Nevertheless, caution is indicated in the coadministration of TCAs with any of the SSRIs and also in switching from one class to the other. Of particular importance, sufficient time must elapse before initiating TCA treatment in a patient being withdrawn from fluoxetine, given the long half-life of the parent and active metabolite (at least 5 weeks may be necessary).
Concomitant use of tricyclic antidepressants with drugs that can inhibit cytochrome P450 2D6 may require lower doses than usually prescribed for either the tricyclic antidepressant or the other drug. Furthermore, whenever one of these other drugs is withdrawn from co-therapy, an increased dose of tricyclic antidepressant may be required. It is desirable to monitor TCA plasma levels whenever a TCA is going to be coadministered with another drug known to be an inhibitor of P450 2D6.
Monoamine oxidase inhibitors – see section. Guanethidine or similarly acting compounds; thyroid medication; alcohol, barbiturates and other CNS depressants; and disulfiram – see section.
When amitriptyline is given with anticholinergic agents or sympathomimetic drugs, including epinephrine combined with local anesthetics, close supervision and careful adjustment of dosages are required.
Hyperpyrexia has been reported when amitriptyline is administered with anticholinergic agents or with neuroleptic drugs, particularly during hot weather.
Paralytic ileus may occur in patients taking tricyclic antidepressants in combination with anticholinergic-type drugs.
Cimetidine is reported to reduce hepatic metabolism of certain tricyclic antidepressants, thereby delaying elimination and increasing steady-state concentrations of these drugs. Clinically significant effects have been reported with the tricyclic antidepressants when used concomitantly with cimetidine. Increases in plasma levels of tricyclic antidepressants, and in the frequency and severity of side effects, particularly anticholinergic, have been reported when cimetidine was added to the drug regimen. Discontinuation of cimetidine in well-controlled patients receiving tricyclic antidepressants and cimetidine may decrease the plasma levels and efficacy of the antidepressants.
Caution is advised if patients receive large doses of ethchlorvynol concurrently. Transient delirium has been reported in patients who were treated with one gram of ethchlorvynol and 75 to 150 mg of amitriptyline hydrochloride.
TTP/HUS, in some cases resulting in death, has occurred in patients with advanced HIV─1 disease and also in allogeneic bone marrow transplant and renal transplant recipients participating in clinical trials of VALTREX at doses of 8 grams per day. Treatment with VALTREX should be stopped immediately if clinical signs, symptoms, and laboratory abnormalities consistent with TTP/HUS occur.
The following serious adverse reactions are discussed in greater detail in other sections of the labeling:
The most common adverse reactions reported in at least 1 indication by greater than 10% of adult subjects treated with VALTREX and observed more frequently with VALTREX compared to placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in greater than 10% of pediatric subjects aged less than 18 years was headache.
Reference
This information is obtained from the National Institute of Health's Standard Packaging Label drug database.
"https://dailymed.nlm.nih.gov/dailymed/"
While we update our database periodically, we cannot guarantee it is always updated to the latest version.
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