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These highlights do not include all the information needed to use VALTREX safely and effectively. See full prescribing information for VALTREX. VALTREX (valacyclovir hydrochloride) CapletsInitial U.S. Approval: 1995 | VALTREX

05:26 EDT 27th August 2014 | BioPortfolio

Note: While we endeavour to keep our records up-to-date one should not rely on these details being accurate without first consulting a professional. Click here to read our full medical disclaimer.

Cold Sores (Herpes Labialis): VALTREX is indicated for treatment of cold sores (herpes labialis). The efficacy of VALTREX initiated after the development of clinical signs of a cold sore (e.g., papule, vesicle, or ulcer) has not been established.

Genital Herpes: Initial Episode: VALTREX is indicated for treatment of the initial episode of genital herpes in immunocompetent adults. The efficacy of treatment with VALTREX when initiated more than 72 hours after the onset of signs and symptoms has not been established.

Recurrent Episodes: VALTREX is indicated for treatment of recurrent episodes of genital herpes in immunocompetent adults. The efficacy of treatment with VALTREX when initiated more than 24 hours after the onset of signs and symptoms has not been established.

Suppressive Therapy: VALTREX is indicated for chronic suppressive therapy of recurrent episodes of genital herpes in immunocompetent and in HIV-infected adults. The efficacy and safety of VALTREX for the suppression of genital herpes beyond 1 year in immunocompetent patients and beyond 6 months in HIV-infected patients have not been established.

Reduction of Transmission: VALTREX is indicated for the reduction of transmission of genital herpes in immunocompetent adults. The efficacy of VALTREX for the reduction of transmission of genital herpes beyond 8 months in discordant couples has not been established. The efficacy of VALTREX for the reduction of transmission of genital herpes in individuals with multiple partners and non-heterosexual couples has not been established. Safer sex practices should be used with suppressive therapy (see current Centers for Disease Control and Prevention [CDC] Sexually Transmitted Diseases Treatment Guidelines).

Herpes Zoster: VALTREX is indicated for the treatment of herpes zoster (shingles) in immunocompetent adults. The efficacy of VALTREX when initiated more than 72 hours after the onset of rash and the efficacy and safety of VALTREX for treatment of disseminated herpes zoster have not been established.

Cold Sores (Herpes Labialis): VALTREX is indicated for the treatment of cold sores (herpes labialis) in pediatric patients ≥12 years of age. The efficacy of VALTREX initiated after the development of clinical signs of a cold sore (e.g., papule, vesicle, or ulcer) has not been established.

Chickenpox: VALTREX is indicated for the treatment of chickenpox in immunocompetent pediatric patients 2 to <18 years of age. Based on efficacy data from clinical studies with oral acyclovir, treatment with VALTREX should be initiated within 24 hours after the onset of rash [see Clinical Studies (14.4)].

The efficacy and safety of VALTREX have not been established in:

Cold Sores (Herpes Labialis): The recommended dosage of VALTREX for treatment of cold sores is 2 grams twice daily for 1 day taken 12 hours apart. Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning).

Genital Herpes: Initial Episode: The recommended dosage of VALTREX for treatment of initial genital herpes is 1 gram twice daily for 10 days. Therapy was most effective when administered within 48 hours of the onset of signs and symptoms.

Recurrent Episodes: The recommended dosage of VALTREX for treatment of recurrent genital herpes is 500 mg twice daily for 3 days. Initiate treatment at the first sign or symptom of an episode.

Suppressive Therapy: The recommended dosage of VALTREX for chronic suppressive therapy of recurrent genital herpes is 1 gram once daily in patients with normal immune function. In patients with a history of 9 or fewer recurrences per year, an alternative dose is 500 mg once daily.

In HIV-infected patients with a CD4+ cell count ≥100 cells/mm, the recommended dosage of VALTREX for chronic suppressive therapy of recurrent genital herpes is 500 mg twice daily.

Reduction of Transmission: The recommended dosage of VALTREX for reduction of transmission of genital herpes in patients with a history of 9 or fewer recurrences per year is 500 mg once daily for the source partner.

Herpes Zoster: The recommended dosage of VALTREX for treatment of herpes zoster is 1 gram 3 times daily for 7 days. Therapy should be initiated at the earliest sign or symptom of herpes zoster and is most effective when started within 48 hours of the onset of rash.

Cold Sores (Herpes Labialis): The recommended dosage of VALTREX for the treatment of cold sores in pediatric patients ≥12 years of age is 2 grams twice daily for 1 day taken 12 hours apart. Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning).

Chickenpox: The recommended dosage of VALTREX for treatment of chickenpox in immunocompetent pediatric patients 2 to <18 years of age is 20 mg/kg administered 3 times daily for 5 days. The total dose should not exceed 1 gram 3 times daily. Therapy should be initiated at the earliest sign or symptom [see Use in Specific Populations (8.4), Clinical Pharmacology (12.3), Clinical Studies (14.4)].

Ingredients and Preparation per USP-NF: VALTREX Caplets 500 mg, cherry flavor, and Suspension Structured Vehicle USP-NF (SSV). Valacyclovir oral suspension (25 mg/mL or 50 mg/mL) should be prepared in lots of 100 mL.

Prepare Suspension at Time of Dispensing as Follows:

* The amount of cherry flavor added is as instructed by the suppliers of the cherry flavor.

Dosage recommendations for adult patients with reduced renal function are provided in Table 1 [see Use in Specific Populations (8.5, 8.6), Clinical Pharmacology (12.3)]. Data are not available for the use of VALTREX in pediatric patients with a creatinine clearance <50 mL/min/1.73 m.

Hemodialysis: Patients requiring hemodialysis should receive the recommended dose of VALTREX after hemodialysis. During hemodialysis, the half-life of acyclovir after administration of VALTREX is approximately 4 hours. About one third of acyclovir in the body is removed by dialysis during a 4-hour hemodialysis session.

Peritoneal Dialysis: There is no information specific to administration of VALTREX in patients receiving peritoneal dialysis. The effect of chronic ambulatory peritoneal dialysis (CAPD) and continuous arteriovenous hemofiltration/dialysis (CAVHD) on acyclovir pharmacokinetics has been studied. The removal of acyclovir after CAPD and CAVHD is less pronounced than with hemodialysis, and the pharmacokinetic parameters closely resemble those observed in patients with end-stage renal disease (ESRD) not receiving hemodialysis. Therefore, supplemental doses of VALTREX should not be required following CAPD or CAVHD.

Table 1. VALTREX Dosage Recommendations for Adults With Renal Impairment
Indications Normal Dosage Regimen (Creatinine Clearance ≥50 mL/min) Creatinine Clearance (mL/min)
30-49 10-29 <10
Cold sores (Herpes labialis)   Do not exceed 1 day of treatment. Two 2 gram doses taken 12 hours apart Two 1 gram doses taken 12 hours apart Two 500 mg doses taken 12 hours apart 500 mg single dose
Genital herpes:  Initial episode 1 gram every 12 hours no reduction 1 gram every 24 hours 500 mg every 24 hours
Genital herpes:  Recurrent episode 500 mg every 12 hours no reduction 500 mg every 24 hours 500 mg every 24 hours
Genital herpes:  Suppressive therapy
   Immunocompetent patients   1 gram every 24 hours no reduction 500 mg every 24 hours 500 mg every 24 hours
   Alternate dose for immunocompetent patients with ≤9 recurrences/year   500 mg every 24 hours no reduction 500 mg every 48 hours 500 mg every 48 hours
   HIV-infected patients 500 mg every 12 hours no reduction 500 mg every 24 hours 500 mg every 24 hours
Herpes zoster 1 gram every 8 hours 1 gram every 12 hours 1 gram every 24 hours 500 mg every 24 hours

Caplets:

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 [see Adverse Reactions (6.3)].

TTP/HUS, in some cases resulting in death, has occurred in patients with advanced HIV 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.

Cases of acute renal failure have been reported in:

In the event of acute renal failure and anuria, the patient may benefit from hemodialysis until renal function is restored [see Dosage and Administration (2.4), Adverse Reactions (6.3)].

Central nervous system adverse reactions, including agitation, hallucinations, confusion, delirium, seizures, and encephalopathy, have been reported in elderly patients with or without reduced renal function and in patients with underlying renal disease who received higher than recommended doses of VALTREX for their level of renal function. VALTREX should be discontinued if central nervous system adverse reactions occur [see Adverse Reactions (6.3), Use in Specific Populations (8.5, 8.6)].

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 >10% of adult patients treated with VALTREX and observed more frequently with VALTREX compared to placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in >10% of pediatric patients <18 years of age was headache.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Cold Sores (Herpes Labialis): In clinical studies for the treatment of cold sores, the adverse reactions reported by patients receiving VALTREX 2 grams twice daily (n = 609) or placebo (n = 609) for 1 day, respectively, included headache (14%, 10%) and dizziness (2%, 1%). The frequencies of abnormal ALT (>2 x ULN) were 1.8% for patients receiving VALTREX compared with 0.8% for placebo. Other laboratory abnormalities (hemoglobin, white blood cells, alkaline phosphatase, and serum creatinine) occurred with similar frequencies in the 2 groups.

Genital Herpes: Initial Episode: In a clinical study for the treatment of initial episodes of genital herpes, the adverse reactions reported by ≥5% of patients receiving VALTREX 1 gram twice daily for 10 days (n = 318) or oral acyclovir 200 mg 5 times daily for 10 days (n = 318), respectively, included headache (13%, 10%) and nausea (6%, 6%). For the incidence of laboratory abnormalities see Table 2.

Recurrent Episodes: In 3 clinical studies for the episodic treatment of recurrent genital herpes, the adverse reactions reported by ≥5% of patients receiving VALTREX 500 mg twice daily for 3 days (n = 402), VALTREX 500 mg twice daily for 5 days (n = 1,136) or placebo (n = 259), respectively, included headache (16%, 11%, 14%) and nausea (5%, 4%, 5%). For the incidence of laboratory abnormalities see Table 2.

Suppressive Therapy: Suppression of Recurrent Genital Herpes in Immunocompetent Adults: In a clinical study for the suppression of recurrent genital herpes infections, the adverse reactions reported by patients receiving VALTREX 1 gram once daily (n = 269), VALTREX 500 mg once daily (n = 266), or placebo (n = 134), respectively, included headache (35%, 38%, 34%), nausea (11%, 11%, 8%), abdominal pain (11%, 9%, 6%), dysmenorrhea (8%, 5%, 4%), depression (7%, 5%, 5%), arthralgia (6%, 5%, 4%), vomiting (3%, 3%, 2%), and dizziness (4%, 2%, 1%). For the incidence of laboratory abnormalities see Table 2.

Suppression of Recurrent Genital Herpes in HIV-Infected Patients: In HIV-infected patients, frequently reported adverse reactions for VALTREX (500 mg twice daily; n = 194, median days on therapy = 172) and placebo (n = 99, median days on therapy = 59), respectively, included headache (13%, 8%), fatigue (8%, 5%), and rash (8%, 1%). Post-randomization laboratory abnormalities that were reported more frequently in valacyclovir subjects versus placebo included elevated alkaline phosphatase (4%, 2%), elevated ALT (14%, 10%), elevated AST (16%, 11%), decreased neutrophil counts (18%, 10%), and decreased platelet counts (3%, 0%), respectively.

Reduction of Transmission: In a clinical study for the reduction of transmission of genital herpes, the adverse reactions reported by patients receiving VALTREX 500 mg once daily (n = 743) or placebo once daily (n = 741), respectively, included headache (29%, 26%), nasopharyngitis (16%, 15%), and upper respiratory tract infection (9%, 10%).

Herpes Zoster: In 2 clinical studies for the treatment of herpes zoster, the adverse reactions reported by patients receiving VALTREX 1 gram 3 times daily for 7 to 14 days (n = 967) or placebo (n = 195), respectively, included nausea (15%, 8%), headache (14%, 12%), vomiting (6%, 3%), dizziness (3%, 2%), and abdominal pain (3%, 2%). For the incidence of laboratory abnormalities see Table 2.

Table 2. Incidence (%) of Laboratory Abnormalities in Herpes Zoster and Genital Herpes Study Populations
Laboratory Abnormality Herpes Zoster Genital Herpes Treatment Genital Herpes Suppression
VALTREX 1 gram 3 times daily(n = 967) Placebo(n = 195) VALTREX 1 gram twice daily(n = 1,194) VALTREX 500 mg twice daily(n = 1,159) Placebo(n = 439) VALTREX 1 gram once daily(n = 269) VALTREX 500 mg once daily(n = 266) Placebo(n = 134)
Hemoglobin (<0.8 x LLN) 0.8% 0% 0.3% 0.2% 0% 0% 0.8% 0.8%
White blood cells(<0.75 x LLN) 1.3% 0.6% 0.7% 0.6% 0.2% 0.7% 0.8% 1.5%
Platelet count (<100,000/mm3) 1.0% 1.2% 0.3% 0.1% 0.7% 0.4% 1.1% 1.5%
AST (SGOT)(>2 x ULN) 1.0% 0% 1.0% * 0.5% 4.1% 3.8% 3.0%
Serum creatinine(>1.5 x ULN) 0.2% 0% 0.7% 0% 0% 0% 0% 0%
* Data were not collected prospectively.
LLN = Lower limit of normal.
ULN = Upper limit of normal.

The safety profile of VALTREX has been studied in 177 pediatric patients 1 month to <18 years of age. Sixty-five of these pediatric patients, 12 to <18 years of age, received oral caplets for 1 to 2 days for treatment of cold sores. The remaining 112 pediatric patients, 1 month to <12 years of age, participated in 3 pharmacokinetic and safety studies and received valacyclovir oral suspension. Fifty-one of these 112 pediatric patients received oral suspension for 3 to 6 days. The frequency, intensity, and nature of clinical adverse reactions and laboratory abnormalities were similar to those seen in adults.

Pediatric Patients 12 to <18 Years of Age (Cold Sores): In clinical studies for the treatment of cold sores, the adverse reactions reported by adolescent patients receiving VALTREX 2 grams twice daily for 1 day, or VALTREX 2 grams twice daily for 1 day followed by 1 gram twice daily for 1 day (n = 65, across both dosing groups), or placebo (n = 30), respectively, included headache (17%, 3%) and nausea (8%, 0%).

Pediatric Patients 1 Month to <12 Years of Age: Adverse events reported in more than 1 subject across the 3 pharmacokinetic and safety studies in children 1 month to <12 years of age were diarrhea (5%), pyrexia (4%), dehydration (2%), herpes simplex (2%), and rhinorrhea (2%). No clinically meaningful changes in laboratory values were observed.

In addition to adverse events reported from clinical trials, the following events have been identified during postmarketing use of VALTREX. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to VALTREX.

General: Facial edema, hypertension, tachycardia.

Allergic: Acute hypersensitivity reactions including anaphylaxis, angioedema, dyspnea, pruritus, rash, and urticaria [see Contraindications (4)].

CNS Symptoms: Aggressive behavior; agitation; ataxia; coma; confusion; decreased consciousness; dysarthria; encephalopathy; mania; and psychosis, including auditory and visual hallucinations, seizures, tremors [see Warnings and Precautions (5.3), Use in Specific Populations (8.5), (8.6)].

Eye: Visual abnormalities.

Gastrointestinal: Diarrhea.

Hepatobiliary Tract and Pancreas: Liver enzyme abnormalities, hepatitis.

Renal: Renal failure, renal pain (may be associated with renal failure) [see Warnings and Precautions (5.2), Use in Specific Populations (8.5), (8.6)].

Hematologic: Thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis, TTP/HUS [see Warnings and Precautions (5.1)].

Skin: Erythema multiforme, rashes including photosensitivity, alopecia.

No clinically significant drug-drug or drug-food interactions with VALTREX are known [see Clinical Pharmacology (12.3)].

Pregnancy Category B. There are no adequate and well-controlled studies of VALTREX or acyclovir in pregnant women. Based on prospective pregnancy registry data on 749 pregnancies, the overall rate of birth defects in infants exposed to acyclovir in-utero appears similar to the rate for infants in the general population. VALTREX should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

A prospective epidemiologic registry of acyclovir use during pregnancy was established in 1984 and completed in April 1999. There were 749 pregnancies followed in women exposed to systemic acyclovir during the first trimester of pregnancy resulting in 756 outcomes. The occurrence rate of birth defects approximates that found in the general population. However, the small size of the registry is insufficient to evaluate the risk for less common defects or to permit reliable or definitive conclusions regarding the safety of acyclovir in pregnant women and their developing fetuses.

Animal reproduction studies performed at oral doses that provided up to 10 and 7 times the human plasma levels during the period of major organogenesis in rats and rabbits, respectively, revealed no evidence of teratogenicity.

Following oral administration of a 500 mg dose of VALTREX to 5 nursing mothers, peak acyclovir concentrations (C) in breast milk ranged from 0.5 to 2.3 times (median 1.4) the corresponding maternal acyclovir serum concentrations. The acyclovir breast milk AUC ranged from 1.4 to 2.6 times (median 2.2) maternal serum AUC. A 500 mg maternal dosage of VALTREX twice daily would provide a nursing infant with an oral acyclovir dosage of approximately 0.6 mg/kg/day. This would result in less than 2% of the exposure obtained after administration of a standard neonatal dose of 30 mg/kg/day of intravenous acyclovir to the nursing infant. Unchanged valacyclovir was not detected in maternal serum, breast milk, or infant urine. Caution should be exercised when VALTREX is administered to a nursing woman.

VALTREX is indicated for treatment of cold sores in pediatric patients ≥12 years of age and for treatment of chickenpox in pediatric patients 2 to <18 years of age [see Indications and Usage (1.2), Dosage and Administration (2.2)].

The use of VALTREX for treatment of cold sores is based on 2 double-blind, placebo-controlled clinical trials in healthy adults and adolescents (≥12 years of age) with a history of recurrent cold sores [see Clinical Studies (14.1)].

The use of VALTREX for treatment of chickenpox in pediatric patients 2 to <18 years of age is based on single-dose pharmacokinetic and multiple-dose safety data from an open-label trial with valacyclovir and supported by efficacy and safety data from 3 randomized, double-blind, placebo-controlled trials evaluating oral acyclovir in pediatric patients with chickenpox [see Dosage and Administration (2.2), Adverse Reactions (6.2), Clinical Pharmacology (12.3), Clinical Studies (14.4)].

The efficacy and safety of valacyclovir have not been established in pediatric patients:

The pharmacokinetic profile and safety of valacyclovir oral suspension in children <12 years of age were studied in 3 open-label studies. No efficacy evaluations were conducted in any of the 3 studies.

Study 1 was a single-dose pharmacokinetic, multiple-dose safety study in 27 pediatric patients 1 to <12 years of age with clinically suspected varicella-zoster virus (VZV) infection [see Dosage and Administration (2.2), Adverse Reactions (6.2), Clinical Pharmacology (12.3), Clinical Studies (14.4)].

Study 2 was a single-dose pharmacokinetic and safety study in pediatric patients 1 month to <6 years of age who had an active herpes virus infection or who were at risk for herpes virus infection. Fifty-seven subjects were enrolled and received a single dose of 25 mg/kg valacyclovir oral suspension. In infants and children 3 months to <6 years of age, this dose provided comparable systemic acyclovir exposures to that from a 1 gram dose of valacyclovir in adults (historical data). In infants 1 month to <3 months of age, mean acyclovir exposures resulting from a 25 mg/kg dose were higher (C: ↑30%, AUC: ↑60%) than acyclovir exposures following a 1 gram dose of valacyclovir in adults. Acyclovir is not approved for suppressive therapy in infants and children following neonatal HSV infections; therefore valacyclovir is not recommended for this indication because efficacy cannot be extrapolated from acyclovir.

Study 3 was a single-dose pharmacokinetic, multiple-dose safety study in 28 pediatric patients 1 to <12 years of age with clinically suspected HSV infection. None of the children enrolled in this study had genital herpes. Each subject was dosed with valacyclovir oral suspension, 10 mg/kg twice daily for 3 to 5 days. Acyclovir systemic exposures in pediatric patients following valacyclovir oral suspension were compared with historical acyclovir systemic exposures in immunocompetent adults receiving the solid oral dosage form of valacyclovir or acyclovir for the treatment of recurrent genital herpes. The mean projected daily acyclovir systemic exposures in pediatric patients across all age-groups (1 to <12 years of age) were lower (C: ↓20%, AUC: ↓33%) compared with the acyclovir systemic exposures in adults receiving valacyclovir 500 mg twice daily, but were higher (daily AUC: ↑16%) than systemic exposures in adults receiving acyclovir 200 mg 5 times daily. Insufficient data are available to support valacyclovir for the treatment of recurrent genital herpes in this age-group because clinical information on recurrent genital herpes in young children is limited; therefore, extrapolating efficacy data from adults to this population is not possible. Moreover, valacyclovir has not been studied in children 1 to <12 years of age with recurrent genital herpes.

Of the total number of subjects in clinical studies of VALTREX, 906 were 65 and over, and 352 were 75 and over. In a clinical study of herpes zoster, the duration of pain after healing (post-herpetic neuralgia) was longer in patients 65 and older compared with younger adults. Elderly patients are more likely to have reduced renal function and require dose reduction. Elderly patients are also more likely to have renal or CNS adverse events [see Dosage and Administration (2.4), Warnings and Precautions (5.2, 5.3), Clinical Pharmacology (12.3)].

Dosage reduction is recommended when administering VALTREX to patients with renal impairment [see Dosage and Administration (2.4), Warnings and Precautions (5.2, 5.3)].

Caution should be exercised to prevent inadvertent overdose [see Use in Specific Populations (8.5), (8.6)]. 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 [see Dosage and Administration (2.4)].

VALTREX (valacyclovir hydrochloride) is the hydrochloride salt of the L-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 L-valine, 2-[(2-amino-1,6-dihydro-6-oxo-9H-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.

IMAGE 61ea67c2-8c0e-486f-8c0c-6167a1d3d95a-01.jpg

Valacyclovir is an antiviral drug [see Clinical Pharmacology (12.4)].

The pharmacokinetics of valacyclovir and acyclovir after oral administration of VALTREX have been investigated in 14 volunteer studies involving 283 adults and in 3 studies involving 112 pediatric subjects from 1 month to <12 years of age.

Pharmacokinetics in Adults: Absorption and Bioavailability: After oral administration, valacyclovir hydrochloride is rapidly absorbed from the gastrointestinal tract and nearly completely converted to acyclovir and L-valine by first-pass intestinal and/or hepatic metabolism.

The absolute bioavailability of acyclovir after administration of VALTREX is 54.5% ± 9.1% as determined following a 1 gram oral dose of VALTREX and a 350 mg intravenous acyclovir dose to 12 healthy volunteers. Acyclovir bioavailability from the administration of VALTREX is not altered by administration with food (30 minutes after an 873 Kcal breakfast, which included 51 grams of fat).

Acyclovir pharmacokinetic parameter estimates following administration of VALTREX to healthy adult volunteers are presented in Table 3. There was a less than dose-proportional increase in acyclovir maximum concentration (C) and area under the acyclovir concentration-time curve (AUC) after single-dose and multiple-dose administration (4 times daily) of VALTREX from doses between 250 mg to 1 gram.

There is no accumulation of acyclovir after the administration of valacyclovir at the recommended dosage regimens in adults with normal renal function.

Distribution: The binding of valacyclovir to human plasma proteins ranges from 13.5% to 17.9%. The binding of acyclovir to human plasma proteins ranges from 9% to 33%.

Metabolism: Valacyclovir is converted to acyclovir and L-valine by first-pass intestinal and/or hepatic metabolism. Acyclovir is converted to a small extent to inactive metabolites by aldehyde oxidase and by alcohol and aldehyde dehydrogenase. Neither valacyclovir nor acyclovir is metabolized by cytochrome P450 enzymes. Plasma concentrations of unconverted valacyclovir are low and transient, generally becoming non-quantifiable by 3 hours after administration. Peak plasma valacyclovir concentrations are generally less than 0.5 mcg/mL at all doses. After single-dose administration of 1 gram of VALTREX, average plasma valacyclovir concentrations observed were 0.5, 0.4, and 0.8 mcg/mL in patients with hepatic dysfunction, renal insufficiency, and in healthy volunteers who received concomitant cimetidine and probenecid, respectively.

Elimination: The pharmacokinetic disposition of acyclovir delivered by valacyclovir is consistent with previous experience from intravenous and oral acyclovir. Following the oral administration of a single 1 gram dose of radiolabeled valacyclovir to 4 healthy subjects, 46% and 47% of administered radioactivity was recovered in urine and feces, respectively, over 96 hours. Acyclovir accounted for 89% of the radioactivity excreted in the urine. Renal clearance of acyclovir following the administration of a single 1 gram dose of VALTREX to 12 healthy volunteers was approximately 255 ± 86 mL/min which represents 42% of total acyclovir apparent plasma clearance.

The plasma elimination half-life of acyclovir typically averaged 2.5 to 3.3 hours in all studies of VALTREX in volunteers with normal renal function.

Specific Populations: Renal Impairment: Reduction in dosage is recommended in patients with renal impairment [see Dosage and Administration (2.4), Use in Specific Populations (8.5), (8.6)].

Following administration of VALTREX to volunteers with ESRD, the average acyclovir half-life is approximately 14 hours. During hemodialysis, the acyclovir half-life is approximately 4 hours. Approximately one third of acyclovir in the body is removed by dialysis during a 4-hour hemodialysis session. Apparent plasma clearance of acyclovir in dialysis patients was 86.3 ± 21.3 mL/min/1.73 m compared with 679.16 ± 162.76 mL/min/1.73 m in healthy volunteers.

Hepatic Impairment: Administration of VALTREX to patients with moderate (biopsy-proven cirrhosis) or severe (with and without ascites and biopsy-proven cirrhosis) liver disease indicated that the rate but not the extent of conversion of valacyclovir to acyclovir is reduced, and the acyclovir half-life is not affected. Dosage modification is not recommended for patients with cirrhosis.

HIV Disease: In 9 patients with HIV disease and CD4+ cell counts <150 cells/mm who received VALTREX at a dosage of 1 gram 4 times daily for 30 days, the pharmacokinetics of valacyclovir and acyclovir were not different from that observed in healthy volunteers.

Geriatrics: After single-dose administration of 1 gram of VALTREX in healthy geriatric volunteers, the half-life of acyclovir was 3.11 ± 0.51 hours, compared with 2.91 ± 0.63 hours in healthy younger adult volunteers. The pharmacokinetics of acyclovir following single- and multiple-dose oral administration of VALTREX in geriatric volunteers varied with renal function. Dose reduction may be required in geriatric patients, depending on the underlying renal status of the patient [see Dosage and Administration (2.4), Use in Specific Populations (8.5), (8.6)].

Pediatrics: Acyclovir pharmacokinetics have been evaluated in a total of 98 pediatric patients (1 month to <12 years of age) following administration of the first dose of an extemporaneous oral suspension of valacyclovir [see Adverse Reactions (6.2), Use in Specific Populations (8.4)]. Acyclovir pharmacokinetic parameter estimates following a 20 mg/kg dose are provided in Table 4.

Drug Interactions: When VALTREX is coadministered with antacids, cimetidine and/or probenicid, digoxin, or thiazide diuretics in patients with normal renal function, the effects are not considered to be of clinical significance (see below). Therefore, when VALTREX is coadministered with these drugs in patients with normal renal function, no dosage adjustment is recommended.

Antacids: The pharmacokinetics of acyclovir after a single dose of VALTREX (1 gram) were unchanged by coadministration of a single dose of antacids (Al or Mg).

Cimetidine: Acyclovir C and AUC following a single dose of VALTREX (1 gram) increased by 8% and 32%, respectively, after a single dose of cimetidine (800 mg).

Cimetidine Plus Probenecid: Acyclovir C and AUC following a single dose of VALTREX (1 gram) increased by 30% and 78%, respectively, after a combination of cimetidine and probenecid, primarily due to a reduction in renal clearance of acyclovir.

Digoxin: The pharmacokinetics of digoxin were not affected by coadministration of VALTREX 1 gram 3 times daily, and the pharmacokinetics of acyclovir after a single dose of VALTREX (1 gram) was unchanged by coadministration of digoxin (2 doses of 0.75 mg).

Probenecid: Acyclovir C and AUC following a single dose of VALTREX (1 gram) increased by 22% and 49%, respectively, after probenecid (1 gram).

Thiazide Diuretics: The pharmacokinetics of acyclovir after a single dose of VALTREX (1 gram) were unchanged by coadministration of multiple doses of thiazide diuretics.

Table 3. Mean (±SD) Plasma Acyclovir Pharmacokinetic Parameters Following Administration of VALTREX to Healthy Adult Volunteers
Dose Single-Dose Administration(N = 8) Multiple-Dose Administration* (N = 24, 8 per treatment arm)
Cmax (±SD) (mcg/mL) AUC (±SD) (hr●mcg/mL) Cmax (±SD) (mcg/mL) AUC (±SD) (hr●mcg/mL)
100 mg 0.83 (±0.14) 2.28 (±0.40) ND ND
250 mg 2.15 (±0.50) 5.76 (±0.60) 2.11 (±0.33) 5.66 (±1.09)
500 mg 3.28 (±0.83) 11.59 (±1.79) 3.69 (±0.87) 9.88 (±2.01)
750 mg 4.17 (±1.14) 14.11 (±3.54) ND ND
1,000 mg 5.65 (±2.37) 19.52 (±6.04) 4.96 (±0.64) 15.70 (±2.27)
* Administered 4 times daily for 11 days.
ND = not done.
Table 4. Mean (±SD) Plasma Acyclovir Pharmacokinetic Parameter Estimates Following First-Dose Administration of 20 mg/kg Valacyclovir Oral Suspension to Pediatric Patients vs. 1 Gram Single Dose of VALTREX to Adults
* Historical estimates using pediatric pharmacokinetic sampling schedule.
Parameter Pediatric Patients(20 mg/kg Oral Suspension) Adults 1 gram Solid Dose of VALTREX* (N = 15)
1 - <2 yr(N = 6) 2 - <6 yr(N = 12) 6 - <12 yr(N = 8)
AUC (mcg•hr/mL) 14.4 (±6.26) 10.1 (±3.35) 13.1 (±3.43) 17.2 (±3.10)
Cmax (mcg/mL) 4.03 (±1.37) 3.75 (±1.14) 4.71 (±1.20) 4.72 (±1.37)

Mechanism of Action: Valacyclovir is a nucleoside analogue DNA polymerase inhibitor. Valacyclovir hydrochloride is rapidly converted to acyclovir which has demonstrated antiviral activity against HSV types 1 (HSV-1) and 2 (HSV-2) and VZV both in cell culture and in vivo.

The inhibitory activity of acyclovir 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, a nucleotide analogue. The monophosphate is further converted into diphosphate by cellular guanylate kinase and into triphosphate by a number of cellular enzymes. In biochemical assays, acyclovir triphosphate inhibits replication of herpes viral DNA. This is accomplished in 3 ways: 1) competitive inhibition of viral DNA polymerase, 2) incorporation and termination of the growing viral DNA chain, and 3) inactivation of the viral DNA polymerase. The greater antiviral activity of acyclovir against HSV compared with VZV is due to its more efficient phosphorylation by the viral TK.

Antiviral Activities: The quantitative relationship between the cell culture susceptibility of herpesviruses to antivirals and the clinical response to therapy has not been established in humans, and virus sensitivity testing has not been standardized. Sensitivity testing results, expressed as the concentration of drug required to inhibit by 50% the growth of virus in cell culture (EC), vary greatly depending upon a number of factors. Using plaque-reduction assays, the EC values against herpes simplex virus isolates range from 0.09 to 60 μM (0.02 to 13.5 mcg/mL) for HSV-1 and from 0.04 to 44 μM (0.01 to 9.9 mcg/mL) for HSV-2. The EC values for acyclovir against most laboratory strains and clinical isolates of VZV range from 0.53 to 48 μM (0.12 to 10.8 mcg/mL). Acyclovir also demonstrates activity against the Oka vaccine strain of VZV with a mean EC of 6 μM (1.35 mcg/mL).

Resistance: Resistance of HSV and VZV to acyclovir can result from qualitative and quantitative changes in the viral TK and/or DNA polymerase. Clinical isolates of VZV with reduced susceptibility to acyclovir have been recovered from patients with AIDS. In these cases, TK-deficient mutants of VZV have been recovered.

Resistance of HSV and VZV to acyclovir occurs by the same mechanisms. While most of the acyclovir-resistant mutants isolated thus far from immunocompromised patients have been found to be TK-deficient mutants, other mutants involving the viral TK gene (TK partial and TK altered) and DNA polymerase have also been isolated. TK-negative mutants may cause severe disease in immunocompromised patients. The possibility of viral resistance to valacyclovir (and therefore, to acyclovir) should be considered in patients who show poor clinical response during therapy.

The data presented below include references to the steady-state acyclovir AUC observed in humans treated with 1 gram VALTREX given orally 3 times a day to treat herpes zoster. Plasma drug concentrations in animal studies are expressed as multiples of human exposure to acyclovir [see Clinical Pharmacology (12.3)].

Valacyclovir was noncarcinogenic in lifetime carcinogenicity bioassays at single daily doses (gavage) of valacyclovir giving plasma acyclovir concentrations equivalent to human levels in the mouse bioassay and 1.4 to 2.3 times human levels in the rat bioassay. There was no significant difference in the incidence of tumors between treated and control animals, nor did valacyclovir shorten the latency of tumors.

Valacyclovir was tested in 5 genetic toxicity assays. An Ames assay was negative in the absence or presence of metabolic activation. Also negative were an in vitro cytogenetic study with human lymphocytes and a rat cytogenetic study.

In the mouse lymphoma assay, valacyclovir was not mutagenic in the absence of metabolic activation. In the presence of metabolic activation (76% to 88% conversion to acyclovir), valacyclovir was mutagenic.

Valacyclovir was mutagenic in a mouse micronucleus assay.

Manufacturer

Cardinal Health, Inc.

Active Ingredients

Source

Drugs and Medications [22 Associated Drugs and Medications listed on BioPortfolio]

Valtrex [GlaxoSmithKline LLC]

These highlights do not include all the information needed to use VALTREX safely and effectively. See full prescribing information for VALTREX. VALTREX (valacyclovir hydrochloride) CapletsInitial U.S...

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These highlights do not include all the information needed to use valacyclovir hydrochloride safely and effectively. See full prescribing information for valacyclovir hydrochloride tablets.valacyclovi...

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Valacyclovir hydrochloride [Actavis Inc.]

Valacyclovir Hydrochloride Tablets These highlights do not include all the information needed to use Valacyclovir hydrochloride safely and effectively. See full prescribing information for Valacyclovi...

Clinical Trials [10 Associated Clinical Trials listed on BioPortfolio]

VALTREX Once Daily For Viral Shedding In Herpes Simplex Virus 2 (HSV-2) Seropositive Subjects

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V3: Vancouver-Victoria Valacyclovir Trial for Early Psychosis

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The purpose of this study is to compare the safety and efficacy of Vacyless® and Valtrex® in patients with acute herpes zoster.

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