Valtrex
valacyclovir hydrochloride (valaciclovir (UK))
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) valacyclovir,Valtrex
(trade name)Classification
Therapeutic: antiviralsIndications
Action
Therapeutic effects
Pharmacokinetics
Time/action profile (blood levels†)
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| PO | unknown | 1.5–2.5 hr | 8–24 hr |
Contraindications/Precautions
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 ZosterRenal 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)
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.