valacyclovir hydrochloride

valacyclovir hydrochloride

(val ah sye' kloe ver)

Valtrex

Pregnancy Category B

Drug class

Antiviral

Therapeutic actions

Antiviral activity; inhibits viral DNA replication and deactivates viral DNA polymerase.

Indications

·        Treatment of herpes zoster (shingles)

·        Episodic treatment of first-episode or recurrent genital herpes in immunocompetent patients

·        Suppression of recurrent episodes of genital herpes in HIV patients

·        Reduction of risk of heterosexual transmission of genital herpes to healthy partners when combined with safe sex practices

·        Treatment of cold sores (herpes labialis) in healthy adults

Contraindications and cautions

·        Contraindicated with allergy to valacyclovir or acyclovir.

·        Use cautiously with pregnancy, renal impairment, thrombotic thrombocytopenic purpura, lactation.

Available forms

Tablets—500 mg, 1 g

Dosages

ADULTS

·        Herpes zoster: 1 g tid PO for 7 days; most effective if started within 48 hr of onset of symptoms.

·        Genital herpes: 1 g PO bid for 7–10 days.

·        Episodic treatment of recurrent genital herpes: 500 mg PO bid for 3 days.

·        Suppression of recurrent episodes of genital herpes: 1 g PO daily; patients with history of less than nine episodes in 1 yr may respond to 500 mg PO daily.

·        Reduction of risk of transmission: 500 mg/day PO daily for the source partner.

·        Cold sores: 2 g PO bid for 1 day.

PEDIATRIC PATIENTS

Safety and efficacy not established.

PATIENTS WITH RENAL IMPAIRMENT

Creatinine Clearance (mL/min)	Dose
> 50	1 g q 8 hr
30–49	1 g q 12 hr
10–29	1 g q 24 hr
< 10	500 mg q 24 hr

Dosage adjustment varies depending on indications

	Normal Dose
Indication	Creatinine clearance > 50	Creatinine clearance 30–49	Creatinine clearance 10–29	Creatinine clearance 10
Herpes zoster	1 g q 8 hr	1 g q 12 hr	1 g q 24 hr	500 mg q 24 hr
Genital herpes initial treatment	1 g q 12 hr	1 g q 12 hr	1 g q 24 hr	500 mg q 24 hr
Genital herpes recurrent episodes	500 mg q 12 hr	500 mg q 12 hr	500 mg q 24 hr	500 mg q 24 hr
Genital herpes suppressive therapy	1 g q 24 hr	1 g q 24 hr	500 mg q 24 hr	500 mg q 24 hr
For 9 or fewer recurrences per year	500 mg q 24 hr	500 mg q 24 hr	500 mg q 48 hr	500 mg q 48 hr

Pharmacokinetics

Route	Onset	Peak
Oral	Rapid	3 hr

Metabolism: Not metabolized; T_1/2: 2.5–3.3 hr

Distribution: Crosses placenta: enters breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Headache, dizziness

·        GI: Nausea, vomiting, diarrhea, anorexia

·        GU: Acute renal failure

Interactions

Drug-drug

·        Decreased rate of effectiveness with probenecid, cimetidine

Nursing considerations

CLINICAL ALERT!

Name confusion has been reported with Valtrex (valacyclovir) and Valcyte (valganciclovir); use caution.

Assessment

·        History: Allergy to valacyclovir, acyclovir; renal disease; lactation; thrombotic thrombocytopenic purpura, pregnancy

·        Physical: Orientation; urinary output; abdominal examination, normal output; BUN, creatinine clearance

Interventions

·        Begin treatment within 72 hr of onset of symptoms of shingles.

·        Administer without regard to meals; administer with meals to decrease GI upset if needed.

·        Provide appropriate analgesics for headache, discomfort of shingles.

·        Advise continued use of safe sex practices.

Teaching points

·        Take this drug without regard to meals; if GI upset is a problem, take with meals.

·        Take the full course of therapy as prescribed.

·        Avoid contact with lesions and avoid intercourse when lesions or symptoms are present to avoid infecting others.

·        Start therapy at first sign of an episode when treating recurrent herpes.

·        You may experience these side effects: Nausea, vomiting, loss of appetite, diarrhea; headache, dizziness.

·        Report severe diarrhea, nausea; headache; worsening of the shingles.

Adverse effects in Italic are most common; those in Bold are life-threatening.