General

Pronunciation
ay-SYE-kloe-veer

Trade Name(s)

• Avirax [Canada]

• Zovirax

Pregnancy Category
Category B (PO, IV) Category C (topical)

Ther. class.
antivirals

Pharm. class.
purine analogues

Indications

• PO: Recurrent genital herpes infections. Localized cutaneous herpes zoster infections (shingles) and chickenpox (varicella)

• IV: Severe initial episodes of genital herpes in nonimmunosuppressed patients. Mucosal or cutaneous herpes simplex infections or herpes zoster infections (shingles) in immunosuppressed patients. Herpes simplex encephalitis

• Topical: Cream—Recurrent herpes labialis (cold sores). Ointment—Treatment of limited non–life-threatening herpes simplex infections in immunocompromised patients (systemic treatment is preferred)

Action

Interferes with viral DNA synthesis

Therapeutic Effect(s):
Inhibition of viral replication, decreased viral shedding, and reduced time for healing of lesions

Pharmacokinetics

Absorption: Despite poor absorption (15–30%), therapeutic blood levels are achieved

Distribution: Widely distributed. CSF concentrations are 50% of plasma. Crosses placenta; enters breast milk

Protein Binding: <30%

Metabolism and Excretion: >90% eliminated unchanged by kidneys; remainder metabolized by liver

Half-life: Neonates: 4 hr; Children 1–12 yr: 2–3 hr; Adults: 2–3.5 hr ( in renal failure)

TIME/ACTION PROFILE (antiviral blood levels)

ROUTE	ONSET	PEAK	DURATION
PO	unknown	1.5–2.5 hr	4 hr
IV	prompt	end of infusion	8 hr

Contraindication/Precautions

Contraindicated in:
Hypersensitivity to acyclovir or valacyclovir

Use Cautiously in:

• Pre-existing serious neurologic, hepatic, pulmonary, or fluid and electrolyte abnormalities

• Renal impairment (dose alteration recommended if CCr <50 ml/min)

• Geriatric patients (due to age related in renal function)

• Obese patients (dose should be based on ideal body weight)

• Patients with hypoxia

• OB: Lactation: Safety not established

Adverse Reactions/Side Effects

CNS: SEIZURES, dizziness, headache, hallucinations, trembling.

GI: diarrhea, nausea, vomiting, elevated liver enzymes, hyperbilirubinemia, abdominal pain, anorexia.

GU: RENAL FAILURE, crystalluria, hematuria.

Derm: acne, hives, skin rashes, unusual sweating, Stevens-Johnson syndrome.

Endo: changes in menstrual cycle.

Hemat: THROMBOTIC THROMBOCYTOPENIC PURPURA/HEMOLYTIC UREMIC SYNDROME (HIGH DOSES IN IMMUNOSUPPRESSED PATIENTS).

Local: pain, phlebitis, local irritation.

MS: joint pain.

Misc: polydipsia.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• Probenecid blood levels of acyclovir

• blood levels and risk of toxicity from theophylline; dose adjustment may be necessary

• blood levels and may effectiveness of valproic acid or hydantoins

• Concurrent use of other nephrotoxic drugs risk of adverse renal effects

• Zidovudine and IT methotrexate may risk of CNS side effects

Route/Dosage

Initial Genital Herpes

• PO (Adults and Children): 200 mg q 4 hr while awake (5 times/day) for 7–10 days or 400 mg q 8 hr for 7–10 days; maximum dose in children: 80 mg/kg/day in 3–5 divided doses.

• IV (Adults and Children): 5 mg/kg q 8 hr or 750 mg/m²/day divided q 8 hr for 5–7 days.

Chronic Suppressive Therapy for Recurrent Genital Herpes

• PO (Adults and Children): 400 mg twice daily or 200 mg 3–5 times/day for up to 12 mo. Maximum dose in children: 80 mg/kg/day in 2–5 divided doses.

Intermittent Therapy for Recurrent Genital Herpes

• PO (Adults and Children): 200 mg q 4 hr while awake (5 times/day) or 400 mg q 8hr or 800 mg q 12 hr for 5 days, start at first sign of symptoms. Maximum dose in children: 80 mg/kg/day in 2–5 divided doses.

Acute Treatment of Herpes Zoster in Immunosuppressed Patients

• PO (Adults): 800 mg q 4 hr while awake (5 times/day) for 7–10 days.
Prophylaxis—400 mg 5 times/day.

• PO (Children): 250–600 mg/m²/dose 4–5 times/day.

Herpes Zoster in Immunocompetent Patients

• PO (Adults and Children): 4000 mg/day in 5 divided doses for 5–7 days, maximum dose in children: 80 mg/kg/day in 5 divided doses.

Chickenpox

• PO (Adults and Children): 20 mg/kg (not to exceed 800 mg/dose) qid for 5 days. Start within 24 hr of rash onset.

Mucosal and Cutaneous Herpes Simplex Infections in Immunosuppressed Patients

• IV (Adults and Children >12 yr): 5 mg/kg q 8 hr for 7 days.

• IV (Children <12 yr): 10 mg/kg q 8 hr for 7 days.

• Topical (Adults): 0.5 in. ribbon of 5%
ointment for every 4-square-in. area q 3 hr (6 times/day) for 7 days.

Herpes Simplex Encephalitis

• IV (Adults): 10 mg/kg q 8 hr for 14–21 days.

• IV (Children 3 mo–12 yr): 10 mg/kg q 8 hr for 14–21 days.

• IV (Children birth–3 mo): 20 mg/kg q 8 hr for 14–21 days.

• IV (Neonates, premature): 10 mg/kg q 12 hr for 14–21 days.

Varicella Zoster Infections in Immunosuppressed Patients

• IV (Adults): 10 mg/kg q 8 hr for 7–10 days.

• IV (Children <12 yr): 10 mg/kg q 8 hr for 7–10 days.

Renal Impairment

• PO, IV (Adults and Children):
CCr >50 ml/min/1.73 m²—no dosage adjustment needed;
CCr 25 –50 ml/min/1.73 m²— administer normal dose q 12 hr;
CCr 10–25 ml/min/1.73 m²— administer normal dose q 24 hr;
CCr 0–10 ml/min/1.73 m²—50% of dose q 24 hr.

• IV (Neonates):
SCr 0.8–1.1 mg/dl:Administer 20 mg/kg/dose q 12 hr;
SCr 1.2–1.5 mg/dl:Administer 20 mg/kg/dose q 24 hr;
SCr >1.5 mg/dl:Administer 10 mg/kg/dose q 24 hr.

Herpes labialis

• Topical (Adults and Children >12 yr): Apply 5 times/day for 4 days; start at first symptoms.

Availability

• Capsules: 200 mg

» Cost:
Generic: $12.99/30.

• Tablets: 400 mg, 800 mg

» Cost:
Generic: 400 mg $14.50/30, 800 mg $24.99/30.

• Suspension (banana flavor): 200 mg/5 ml

» Cost: $123.97/473 ml.

• Powder for injection: 500 mg/vial, 1000 mg/vial

• Solution for injection: 25 mg/ml in 20-ml and 40-ml vials, 50 mg/ml in 10-ml and 20-ml vials

• Cream: 5% in 2-g and 5-g tubes

» Cost: $51.36/2-g tube, $115.99/5-g tube.

• Ointment: 5% in 15-g tubes

» Cost: $129.99/15-g tube.

Assessment

• Assess lesions before and daily during therapy

• Monitor neurologic status in patients with herpes encephalitis

Lab Test Considerations

• Monitor BUN, serum creatinine, and CCr before and during therapy. BUN and serum creatinine levels or CCr may indicate renal failure

Potential Nursing Diagnoses

• Risk for impaired skin integrity (Indications)

• Risk for infection (Patient/Family Teaching)

Implementation

• Acyclovir treatment should be started as soon as possible after herpes simplex symptoms appear and within 24 hr of a herpes zoster outbreak

• PO: Acyclovir may be administered with food or on an empty stomach, with a full glass of water

» Shake oral suspension well before administration

IV Adminstration:

• IV:
Maintain adequate hydration (2000–3000 ml/day), especially during first 2 hr after IV infusion, to prevent crystalluria
Observe infusion site for phlebitis. Rotate infusion site to prevent phlebitis
Acyclovir injectable should not be administered topically, IM, subcut, PO, or in the eye

• Intermittent Infusion:
Diluent: Reconstitute 500-mg or 1-g vial with 10 ml or 20 ml, respectively, of sterile water for injection. Do not reconstitute with bacteriostatic water with benzyl alcohol or parabens. Shake well to dissolve completely. Further dilute in at least 100 ml of D5W, 0.9% NaCl, dextrose/saline combinations or LR.
Concentration: 7 mg/ml. Patients requiring fluid restriction: 10 mg/ml

• Rate:
Administer via infusion pump over 1 hr to minimize renal tubular damage

• Use reconstituted solution within 12 hr. Once diluted for infusion, the solution should be used within 24 hr. Refrigeration results in precipitation, which dissolves at room temperature

• Y-Site Compatibility:

» allopurinol

» amikacin

» amphotericin B cholesteryl sulfate

» ampicillin

» anidulafungin

» cefazolin

» cefotaxime

» cefoxitin

» ceftazidime

» ceftizoxime

» ceftriaxone

» cefuroxime

» chloramphenicol

» cimetidine

» clindamycin

» dexamethasone sodium phosphate

» dimenhydrinate

» diphenhydramine

» docetaxel

» doxorubicin liposome

» doxycycline

» erythromycin lactobionate

» etoposide phosphate

» famotidine

» filgrastim

» fluconazole

» gentamicin

» granisetron

» heparin

» hydrocortisone sodium succinate

» hydromorphone

» imipenem/cilastatin

» lansoprazole

» linezolid

» lorazepam

» magnesium sulfate

» melphalan

» methylprednisolone sodium succinate

» metoclopramide

» metronidazole

» milrinone

» multivitamin infusion

» nafcillin

» oxacillin

» paclitaxel

» pemetrexed

» penicillin G potassium

» pentobarbital

» perphenazine

» piperacillin

» potassium chloride

» propofol

» ranitidine

» remifentanil

» sodium bicarbonate

» teniposide

» theophylline

» thiotepa

» tobramycin

» trimethoprim/sulfamethoxazole

» vancomycin

» zidovudine

• Y-Site Incompatibility:

» amifostine

» aztreonam

» cefepime

» dobutamine

» dopamine

» fludarabine

» foscarnet

» gemcitabine

» idarubicin

» levofloxacin

» ondansetron

» piperacillin/tazobactam

» sargramostim

» tacrolimus

» vinorelbine

• Additive Compatibility:

» fluconazole

• Additive Incompatibility:

» blood products

» pantoprazole

» protein-containing solutions

• Topical: Apply to skin lesions only; do not use in the eye

Patient/Family Teaching

• Advise patient to take medication as directed for the full course of therapy. Take missed doses as soon as possible but not just before next dose is due; do not double doses. Acyclovir should not be used more frequently or longer than prescribed

» Advise patients that the additional use of OTC creams, lotions, and ointments may delay healing and may cause spreading of lesions

» Inform patient that acyclovir is not a cure. The virus lies dormant in the ganglia, and acyclovir will not prevent the spread of infection to others

» Advise patient that condoms should be used during sexual contact and that no sexual contact should be made while lesions are present

» Patient should consult health care professional if symptoms are not relieved after 7 days of topical therapy or if oral acyclovir does not decrease the frequency and severity of recurrences. Immunocompromised patients may require a longer time, usually 2 weeks, for crusting over of lesions

» Instruct women with genital herpes to have yearly Papanicolaou smears because they may be more likely to develop cervical cancer

• Topical: Instruct patient to apply ointment in sufficient quantity to cover all lesions every 3 hr, 6 times/day for 7 days. 0.5-in. ribbon of ointment covers approximately 4 square in. Use a finger cot or glove when applying to prevent inoculation of other areas or spread to other people. Keep affected areas clean and dry. Loose-fitting clothing should be worn to prevent irritation

» Avoid drug contact in or around eyes. Report any unexplained eye symptoms to health care professional immediately; ocular herpetic infection can lead to blindness

Evaluation/Desired Outcomes

• Crusting over and healing of skin lesions

• Decrease in frequency and severity of recurrences

• Acceleration of complete healing and cessation of pain in herpes zoster

• Decrease in intensity of chickenpox

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