Valtrex


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valacyclovir hydrochloride (valaciclovir (UK))

Apo-Valacyclovir, Valtrex

Pharmacologic class: Acyclic purine nucleoside analog

Therapeutic class: Antiviral

Pregnancy risk category B

Action

Rapidly converts to acyclovir, which interferes with viral DNA synthesis and replication

Availability

Caplets: 500 mg, 1 g

Indications and dosages

Herpes zoster (shingles)

Adults: 1 g P.O. t.i.d. for 7 days. Therapy should begin at first sign or symptom of herpes zoster, within 48 hours of onset of zoster rash.

Genital herpes

Adults: For initial episode, 1 g P.O. b.i.d. for 10 days. For recurrent episodes, 500 mg P.O. b.i.d. for 3 days. For chronic suppression, 1 g P.O. daily for no more than 1 year; in patients with history of fewer than nine yearly recurrences, 500 mg P.O. daily for no more than 1 year.

To reduce risk of genital herpes in immunocompetent patients

Adults: 500 mg P.O. daily for source partner, along with counseling regarding safe sex practices

Herpes labialis

Adults: 2 g b.i.d. for 1 day taken 12 hours apart. Begin therapy at first symptom of lesion.

Dosage adjustment

• Renal impairment

Off-label uses

• Cytomegalovirus prophylaxis

Contraindications

• Hypersensitivity to drug, its components, or acyclovir

Precautions

Use cautiously in:
• renal impairment, concurrent use of nephrotoxic drugs, inadequately hydrated patients
• elderly patients
• pregnant or breastfeeding patients
• children.

Administration

• Be aware that therapy may be ineffective if begun more than 72 hours after initial genital herpes outbreak, or more than 24 hours after symptom onset in herpes recurrence.

Adverse reactions

CNS: headache, dizziness, depression, agitation, hallucinations, confusion, encephalopathy

GI: nausea, vomiting, diarrhea, abdominal pain

GU: dysmenorrhea, acute renal failure

Hematologic: anemia, leukopenia, thrombocytopenia, hemolytic uremic syndrome/thrombotic thrombocytopenic purpura/(HUS/TTP)

Musculoskeletal: joint pain

Other: hypersensitivity reaction

Interactions

Drug-drug.Cimetidine, probenecid: increased valacyclovir blood level

Drug-diagnostic tests.Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase: increased levels

Patient monitoring

Monitor CBC. Stay alert for signs and symptoms of blood dyscrasias. Discontinue drug if clinical signs and symptoms and laboratory findings consistent with HUS/TTP occur.
• Assess liver and kidney function tests.

Patient teaching

• Inform patient that herpes transmission can occur even when he is asymptomatic.
• Tell patient and significant other that no cure exists for herpes. Urge them to practice safe sex.
• Inform pregnant patient of risk of neonatal herpes infection.
• Instruct pregnant patient or female of childbearing age to tell health care provider that she has herpes. After delivery, tell her to inform neonatal care providers.

Instruct patient to promptly report unusual bleeding or bruising, urinary changes, or serious adverse CNS reactions.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

valACYclovir

(val-ay-sye-kloe-veer) ,

Valtrex

(trade name)

Classification

Therapeutic: antivirals
Pregnancy Category: B

Indications

Treatment of herpes zoster (shingles).Treatment/suppression of genital herpes.Reduction of transmission of genital herpes.Treatment of chickenpox.Treatment of herpes labialis (cold sores).

Action

Rapidly converted to acyclovir. Acyclovir interferes with viral DNA synthesis.

Therapeutic effects

Inhibited viral replication, decreased viral shedding, reduced time to healing of lesions.
Reduced transmission of genital herpes.

Pharmacokinetics

Absorption: 54% bioavailable as acyclovir after oral administration of valacyclovir.
Distribution: CSF concentrations of acyclovir are 50% of plasma concentrations. Acyclovir crosses placenta; enters breast milk.
Metabolism and Excretion: Rapidly converted to acyclovir via intestinal/hepatic metabolism.
Half-life: 2.5–3.3 hr; up to 14 hr in renal impairment (acyclovir).

Time/action profile (blood levels†)

ROUTEONSETPEAKDURATION
POunknown1.5–2.5 hr8–24 hr
†Acyclovir

Contraindications/Precautions

Contraindicated in: Hypersensitivity to valacyclovir or acyclovir.
Use Cautiously in: Renal impairment (↓ dose/↑ dosing interval recommended if CCr <50 mL/min); Obstetric / Lactation / Pediatric: Pregnancy, lactation, or children <2 yr (safety not established); Geriatric: Dose ↓ may be necessary due to ↑ risk of acute renal failure and CNS side effects.

Adverse Reactions/Side Effects

Central nervous system

  • headache (most frequent)
  • agitation
  • confusion
  • delirium
  • dizziness
  • encephalopathy
  • hallucinations
  • seizures
  • weakness

Gastrointestinal

  • nausea (most frequent)
  • abdominal pain
  • anorexia
  • constipation
  • diarrhea

Genitourinary

  • renal failure (life-threatening)
  • crystalluria

Hematologic

  • thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (very high doses in immunosuppressed patients) (life-threatening)

Interactions

Drug-Drug interaction

Probenecid and cimetidine ↑ blood levels; significant only in renal impairment.Concurrent use of other nephrotoxic drugs ↑ risk of adverse renal effects.

Route/Dosage

Herpes Zoster
Oral (Adults) 1 g 3 times daily for 7 days.
Genital Herpes
Oral (Adults) Initial treatment—1 g twice daily for 10 days. Recurrence—500 mg twice daily for 3 days. Suppression of recurrence—1 g once daily or 500 mg once daily in patients experiencing <10 recurrences/yr. Suppression of recurrence in HIV-infected patients—500 mg q 12 hr. Reduction of transmission—500 mg once daily for source partner.
Herpes Labialis
Oral (Adults and Children ≥12 yr) 2 g then 2 g 12 hr later.
Chickenpox
Oral (Children ≥2 yr) 20 mg/kg 3 times daily for 5 days (not to exceed 1 g 3 times daily).

Renal Impairment

Oral (Adults) CCr 30–49 mL/min—1 g q 12 hr for herpes zoster treatment, no ↓ required for treatment of genital herpes; 1 g then 1 g 12 hr later for herpes labialis. CCr 10–29 mL/min—1 g q 24 hr for initial treatment of genital herpes, 500 mg q 24 hr for treatment of recurrent episodes of genital herpes, 500 mg q 48 hr for suppression of genital herpes in patients with 9 or fewer recurrences/yr, 500 mg q 24 hr for suppression of genital herpes in patients with ≥10 recurrences/yr or HIV-infected patients, 1 g q 24 hr for treatment of herpes zoster; 500 mg then 500 mg 12 hr later for herpes labialis. CCr <10 mL/min—500 mg q 24 hr for initial treatment of genital herpes, 500 mg q 24 hr for treatment of recurrent episodes of genital herpes, 500 mg q 48 hr for suppression of genital herpes in patients with 9 or fewer recurrences/yr, 500 mg q 24 hr for suppression of genital herpes in patients with ≥10 recurrences/yr or HIV-infected patients, 500 mg q 24 hr for treatment of herpes zoster; single 500 mg dose for herpes labialis.

Availability (generic available)

Tablets: 500 mg, 1 g Cost: Generic — 500 mg $31.44 / 30, 1 g $53.34 / 30

Nursing implications

Nursing assessment

  • Assess lesions before and daily during therapy.
  • Monitor patient for signs of thrombotic thrombocytic purpura/hemolytic uremic syndrome (thrombocytopenia, microangiopathic hemolytic anemia, neurologic findings, renal dysfunction, fever). Requires prompt treatment; may be fatal.

Potential Nursing Diagnoses

Risk for impaired skin integrity (Indications)
Risk for infection (Indications,  Patient/Family Teaching)

Implementation

  • high alert: Do not confuse valacyclovir with valganciclovir. Do not confuse Valtrex (valacyclovir) with Valcyte (valganciclovir).
  • Oral: May be administered without regard to meals.
  • Herpes Zoster: Implement valacyclovir therapy as soon as possible after the onset of signs or symptoms of herpes zoster; most effective if started within 48 hr of the onset of zoster rash. Efficacy of treatment started >72 hr after rash onset is unknown.
  • Genital Herpes and Herpes Labialis: Implement treatment for genital herpes as soon as possible after onset of symptoms (tingling, itching, burning).
  • Chicken Pox: Initiate therapy at the earliest sign or symptom; preferably within 24 hr of onset of rash.

Patient/Family Teaching

  • Instruct patient to take valacyclovir exactly as directed for the full course of therapy. Take missed doses as soon as remembered if not just before next dose; do not double doses. Advise patient to read the Patient Information before starting therapy.
  • Advise patient to maintain adequate hydration during therapy.
  • Advise patient to notify health care professional promptly if nervous system symptoms (aggressive behavior, unsteady movement, shaky movements, confusion, speech problems, hallucinations, seizures, coma) occur.
  • Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications.
  • Instruct female patients to notify health care professional if pregnancy is planned or suspected, or if breast feeding.
  • Herpes Zoster: Inform patient that valacyclovir does not prevent the spread of infection to others. Precautions should be taken around others who have not had chickenpox or varicella vaccine, or are immunosuppressed, until all lesions have crusted.
  • Genital Herpes and Herpes Labialis: Inform patient that valacyclovir does not prevent the spread of herpes labialis to others. Advise patient to avoid contact with lesions while lesions or symptoms are present. Valacyclovir reduces transmission of genital herpes to others. Advise patient to practice safe sex (avoid sexual intercourse when lesions are present and wear a condom made of latex or polyurethane during sexual contact).

Evaluation/Desired Outcomes

  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with acute herpes zoster (shingles).
  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with genital herpes.
  • Decrease in frequency of outbreaks in patients with genital herpes.
  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with herpes labialis. Decrease in transmission of genital herpes.
  • Treatment of chickenpox.

Valtrex

(văl′trĕks′)
A trademark for the drug valacyclovir hydrochloride.

Valtrex

A brand name for VALACICLOVIR.
References in periodicals archive ?
But even using condoms and prophylactic therapy with Valtrex cannot guarantee that you won't pass herpes along to your partners.
When he started taking the antiviral Valtrex he started speaking.
He was given tests and prescribed Valtrex to treat a possible herpetic infection.
In mid-December, the Wall Street Journal ran a front-page story describing how GlaxoSmithKline, which makes the anti-herpes medication Valtrex (valacyclovir), has funded researchers and continuing medication seminars to promote universal herpes testing among pregnant women, which could lead to significantly higher drug sales.
Currently, GSK is marketing two agents for GH, Valtrex and Zovirax.
Valtrex offers once-daily dosing for the suppression of genital herpes outbreaks, as well as a three-day treatment for recurrent outbreaks of genital herpes.
Prescription antiviral medicines--including Zovirax (acyclovir), Famvir (famciclovir), and Valtrex (valacyclovir)--may help speed healing and reduce shingles pain if taken within the first 72 hours of symptoms.
The firm said it was sanguine about patent threats to two of its drugs, herpes treatment Valtrex and Imitrex for migraine, following the emergence of challenges this month.
However; a number of other prescription medications were listed in the coroner's report: Depakote, a treatment for epilepsy and the manic episodes associated with bipolar depression; Paxil, an antidepressant; Viagra, a treatment for impotence; Maxzide, a diuretic used in the treatment of high blood pressure; Claritin, an antihistamine; Bextra, an arthritis treatment; Valtrex, a preventive treatment for genital.
Examples of these drugs include Zovirax (acyclovir) or its generic version acyclovir, Valtrex (valacyclovir), Cytovene (ganciclovir), Valcyte (valgancyclovir), and Vistide (cidofovir).
His medications for HIV treatment include sustiva, epivir, AZT, bactrim and valtrex -- all critical for his continued health care maintenance.
Among them are Celebrex, for arthritis; Valtrex, for herpes; Claritin, for allergies; and Zyban, an anti-smoking pill.