Dosing & Uses
Dosage Forms & Strengths
tablet
- 500mg
- 1g
Herpes Labialis
2 g PO q12hr for 1 day
Herpes Zoster
1 g PO q8hr for 7 days (no data on efficacy if started 72 hours after rash)
Genital Herpes
Initial episode: 1 g PO q12hr for 10 days
Recurrent episodes: 500 mg PO q12hr for 3 days (no data on efficacy if started >24 hours after lesion onset)
Suppressive therapy (immunocompetent patients): 1 g/day PO
Suppressive therapy (immunocompetent patients with ≤9 recurrences annually): 500 mg/day PO; transmission reduction for source partner, 500 mg/day PO
Suppressive therapy (HIV-infected patients): 500 mg PO q12hr
Dosing Modifications
Herpes labialis
- CrCl 30-49 mL/min: 1 g PO q12hr for 1 day
- CrCl 10-29 mL/min: 500 mg PO q12hr for 1 day
- CrCl <10 mL/min: 500 mg PO once
Herpes zoster
- CrCl 30-49 mL/min: 1 g PO q12hr
- CrCl 10-29 mL/min: 1 g/day PO
- CrCl <10 mL/min: 500 mg/day PO
Genital herpes (initial episode)
- CrCl 10-29 mL/min: 1 g/day PO
- CrCl <10 mL/min: 500 mg/day PO qDay
Genital herpes (recurrent episodes)
- CrCl ≤29 mL/min: 500 mg/day PO
Genital herpes (suppressive therapy, immunocompetent patients)
- CrCl ≤29 mL/min: 500 mg/day PO
Genital herpes (suppressive therapy, immunocompetent patients with ≥9 recurrences annually)
- CrCl ≤29 mL/min: 500 mg PO q48hr
Genital herpes (suppressive therapy, HIV-infected patients)
- CrCl ≤29 mL/min: 500 mg/day PO
Dosage Forms & Strengths
tablet
- 500mg
- 1g
Chickenpox
<2 years: Safety and efficacy not established
>2 years: 20 mg/kg PO q8hr for 5 days; not to exceed 1 g PO q8hr
Herpes Labialis
<12 years: Safety and efficacy not established
>12 years: 2 g PO q12hr for 1 day
Monitor renal function; dosage may have to be adjusted, depending on renal status
Interactions
Interaction Checker
No Results
Contraindicated
Serious
Significant - Monitor Closely
Minor
Contraindicated (0)
Serious (4)
- bacitracin
valacyclovir and bacitracin both increase nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Avoid concurrent use of bacitracin with other nephrotoxic drugs
- imipenem/cilastatin
valacyclovir, imipenem/cilastatin. unknown mechanism. Avoid or Use Alternate Drug. Coadministration may increase risk of seizures. Avoid unless potential benefit outweighs the risk.
- imipenem/cilastatin/relebactam
valacyclovir, imipenem/cilastatin/relebactam. unknown mechanism. Avoid or Use Alternate Drug. Coadministration may increase risk of seizures. Avoid unless potential benefit outweighs the risk.
- talimogene laherparepvec
valacyclovir decreases effects of talimogene laherparepvec by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Although no drug interactions studies have been performed, antiherpetic viral agents may interfere with the effectiveness of talimogene laherparepvec.
Monitor Closely (6)
- cimetidine
cimetidine increases levels of valacyclovir by decreasing renal clearance. Use Caution/Monitor.
- elvitegravir/cobicistat/emtricitabine/tenofovir DF
valacyclovir, elvitegravir/cobicistat/emtricitabine/tenofovir DF. Either increases toxicity of the other by decreasing renal clearance. Use Caution/Monitor. Toxicity may result from coadministration of emtricitabine and tenofovir with other drugs that are also primarily excreted by glomerular filtration and/or active tubular secretion .
valacyclovir and elvitegravir/cobicistat/emtricitabine/tenofovir DF both increase nephrotoxicity and/or ototoxicity. Use Caution/Monitor. - emtricitabine
valacyclovir increases levels of emtricitabine by Other (see comment). Use Caution/Monitor. Comment: Coadministration of emtricitabine with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of emtricitabine.
- tenofovir DF
valacyclovir increases levels of tenofovir DF by Other (see comment). Use Caution/Monitor. Comment: Coadministration of tenofovir with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of tenofovir.
- ublituximab
ublituximab decreases effects of valacyclovir by immunosuppressive effects; risk of infection. Use Caution/Monitor.
- xanomeline/trospium
valacyclovir, xanomeline/trospium. Either increases levels of the other by decreasing elimination. Use Caution/Monitor. Coadministration of trospium with other drugs eliminated by active tubular secretion may increase plasma concentrations of trospium and/or the concomitantly used drug owing to competition for this elimination pathway. Monitor for increased frequency and/or severity of adverse reactions.
Minor (2)
- probenecid
probenecid increases levels of valacyclovir by decreasing renal clearance. Minor/Significance Unknown.
- zidovudine
valacyclovir increases effects of zidovudine by unknown mechanism. Minor/Significance Unknown. Monitor for lethargy and fatigue.
Adverse Effects
>10%
Headache (14-35%)
Neutropenia (<18%)
Elevated aspartate transaminase (AST) (2-16%)
Nasopharyngitis (<16%)
Nausea (6-15%)
Elevated alanine transaminase (ALT) (<14%)
Abdominal pain (2-11%)
1-10%
Dysmenorrhea (1-8%)
Depression (<7%)
Arthralgia (<1-6%)
Vomiting (<1-6%)
Dizziness (2-4%)
Rash (≤8%)
Rhinorrhea (<2%)
Thrombocytopenia (<3%)
Leukopenia (≤1%)
<1%
Agitation
Aggression
Alopecia
Confusion
Erythema multiforme
Hypertension
Tachycardia
Tremor
Visual disturbances
Warnings
Contraindications
Hypersensitivity to valacyclovir or acyclovir
Cautions
Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) reported in patients with advanced HIV disease and in allogenic bone marrow transplant and renal transplant recipients
Acute renal failure (ARF) may occur, especially in elderly patients or those with underlying renal impairment receiving higher than recommended doses; use with caution in patients with renal impairment, the elderly, and/or patients receiving nephrotoxic drugs
Treatment should begin with the earliest symptom (tingling, burning, itching) in cold sores; for genital herpes, it should begin at the first signs and symptoms (within 72 hours of onset of first diagnosis or 24 hours of onset of recurrent episodes); for herpes zoster, it should begin within 72 hours of onset of rash; for chicken pox, it should begin with the earliest sign or symptom
Central nervous system (CNS) effects may occur (eg, agitation, hallucinations, confusion, encephalopathy); risk of CNS adverse effects is higher in elderly patients
Adequately hydrate patient; decreased precipitation in renal tubules may occur
Pregnancy & Lactation
Pregnancy
Clinical data over several decades with valacyclovir and its metabolite, acyclovir, in pregnant women, have not identified a drug associated risk of major birth defects; there are insufficient data on use of valacyclovir regarding miscarriage or adverse maternal or fetal outcomes; there are risks to fetus associated with untreated herpes simplex during pregnancy
Risk of neonatal HSV infection varies from 30% to 50% for genital HSV acquired in late pregnancy (third trimester), whereas with HSV acquisition in early pregnancy, risk of neonatal infection is about 1%; a primary herpes occurrence during first trimester of pregnancy has been associated with neonatal chorioretinitis, microcephaly, and, in rare cases, skin lesions; in very rare cases, transplacental transmission can occur resulting in congenital infection, including microcephaly, hepatosplenomegaly, intrauterine growth restriction, and stillbirth
Co-infection with HSV increases risk of perinatal HIV transmission in women who had a clinical diagnosis of genital herpes during pregnancy
Animal data
- In animal reproduction studies, no evidence of adverse developmental outcomes was observed with valacyclovir when administered to pregnant rats and rabbits at system exposures (AUC) 4 (rats) and 7 (rabbits) times human exposure at maximum recommended human dose (MRHD)
Lactation
Although there is no information on presence of drug in human milk, its metabolite, acyclovir, is present in human milk following oral administration of drug; based on published data, a 500-mg maternal dose twice daily would provide a breastfed child with an oral acyclovir dosage of approximately 0.6 mg/kg/day; there is no data on effects of drug on breastfed child or on milk production
Consider developmental and health benefits of breastfeeding along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from drug or from underlying maternal condition
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Converted to acyclovir by intestinal and hepatic metabolism
Competes with deoxyguanosine triphosphate for viral DNA polymerase to inhibit DNA synthesis and viral replication
Absorption
Rapidly absorbed
Bioavailability: ~55% (after conversion to acyclovir)
Distribution
Acyclovir (active drug) is widely distributed throughout the body, including brain, kidney, muscle, uterus, lungs, liver, spleen, vagina, and cerebrospoinal fluid (CSF)
Protein bound: 13.5-17.9%
Metabolism
Metabolized by liver; valacyclovir is rapidly and nearly completely converted to acyclovir and L-valine via first-pass effect; acyclovir is hepatically metabolized to a very small extent by aldehyde oxidase and by alcohol and aldehyde dehydrogenase (inactive metabolites)
Elimination
Half-life (normal renal function, adults): Acyclovir, 2.5-3.3 hr; valacyclovir, ~30 min
Half-life (end-stage renal disease): Acyclovir, 14-20 hr
Excretion: Urine (89%), feces (minimal)
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| Valtrex oral - | 1 gram tablet |  | |
| Valtrex oral - | 500 mg tablet |  |
Copyright © 2010 First DataBank, Inc.
Formulary
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