The 2nd :
acyclovir (acycloguanosine)
(ay sye' kloe ver)
Alti-Acyclovir (CAN), Avirax (CAN), Zovirax

Pregnancy Category B

Drug class
Antiviral

Therapeutic actions
Antiviral activity; inhibits viral DNA replication

Indications
· Initial and recurrent mucosal and cutaneous herpes simplex virus (HSV) 1 and 2 and varicella zoster infections in immunocompromised patients
· Severe initial and recurrent genital herpes infections in selected patients
· Herpes simplex encephalitis in patients > 6 mo
· Acute treatment of herpes zoster (shingles) and chickenpox
· Ointment: initial HSV genital infections; limited mucocutaneous HSV infections in immunocompromised patients
· Unlabeled uses: cytomegalovirus and HSV infection following transplant, herpes simplex infections, varicella pneumonia, disseminated primary eczema herpeticum

Contraindications and cautions
· Contraindicated with allergy to acyclovir, seizures, CHF, renal disease, lactation; use caution with pregnancy.

Available forms
Tablets--400, 800 mg; capsules--200 mg; suspension--200 mg/5 mL; powder for injection--500 mg/vial, 1,000 mg/vial; injection--50 mg/mL; ointment--50 mg/g

Dosages
ADULTS
Parenteral
5–10 mg/kg infused IV over 1 hr, q 8 hr (15 mg/kg/day) for 7 days.
Oral
· Initial genital herpes: 200 mg q 4 hr while awake (1,000 mg/day) for 10 days.
· Long-term suppressive therapy: 400 mg bid for up to 12 mo.
· Acute herpes zoster: 800 mg q 4 hr for 7–10 days.
· Chickenpox: 800 mg qid for 5 days.
PEDIATRIC PATIENTS
Parenteral
· < 12 yr: 250–500 mg/m2 infused IV over 1 hr, q 8 hr (750 mg/m2/day) for 7 days.
· > 12 yr: adult dosage.
Oral
Safety not established in children < 2 yr. > 2 yr: 20 mg/kg per dose qid (80 mg/kg/day) for 5 days. Children > 40 kg should receive adult dose.
GERIATRIC PATIENTS OR PATIENTS WITH RENAL IMPAIRMENT
Oral
Creatinine clearance < 10 mL/min: 200 mg q 12 hr.
IV
Creatinine Clearance (mL/min)
Dosage (IV)
> 50
5 mg/kg q 8 hr
25–50
5 mg/kg q 12 hr
10–25
5 mg/kg daily
0–10
2.5 mg/kg daily

Topical
Ointment (all ages): Apply sufficient quantity to cover all lesions 6 times/day (q 3 hr) for 7 days; 1.25-cm (0.5-in) ribbon of ointment covers 2.5 cm2 (4 in2) surface area.

Pharmacokinetics
Route
Onset
Peak
Duration
Oral
Varies
1.5–2 hr

IV
Immediate
1 hr
8 hr


Metabolism: T1/2: 2.5–5 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Unchanged in urine

IV facts
Preparation: Reconstitute 500 mg vial in 10 mL sterile water for injection or bacteriostatic water for injection containing benzyl alcohol, 1,000 mg vial in 20 mL; concentration will be 50 mg/mL. Do not dilute drug with bacteriostatic water containing parabens. Use reconstituted solution within 12 hr; dilute IV solution to concentration of 7 mg/mL or less. Do not use biologic or colloidal fluids such as blood products or protein solutions. Warm drug to room temperature to dissolve precipitates formed during refrigeration.
Infusion: Administer by slow IV infusion of parenteral solutions; avoid bolus or rapid injection. Infuse over at least 1 hr to avoid renal damage.
Incompatibilities: Do not mix with diltiazem, dobutamine, dopamine, fludarabine, foscarnet, idarubicin, meperidine, morphine, ondansetron, piperacillin, sargramostim, vinorelbine.

Adverse effects
Systemic administration
· CNS: Headache, vertigo, depression, tremors, encephalopathic changes
· Dermatologic: Inflammation or phlebitis at injection sites, rash, hair loss
· GI: Nausea, vomiting, diarrhea, anorexia
· GU: Crystalluria with rapid IV administration, hematuria
Topical administration
· Dermatologic: Transient burning at site of application

Interactions
Systemic administration
Drug-drug
· Increased effects with probenecid
· Increased nephrotoxicity with other nephrotoxic drugs
· Extreme drowsiness with zidovudine

Nursing considerations
Assessment
· History: Allergy to acyclovir, seizures, CHF, renal disease, lactation, pregnancy
· Physical: Skin color, lesions; orientation; BP, P, auscultation, perfusion, edema; R, adventitious sounds; urinary output; BUN, creatinine clearance

Interventions
Systemic administration
· Ensure that the patient is well hydrated.
Topical administration
· Start treatment as soon as possible after onset of signs and symptoms.
· Wear a rubber glove or finger cot when applying drug.

Teaching points
Systemic administration
· Complete the full course of oral therapy, and do not exceed the prescribed dose.
· Oral acyclovir is not a cure for your disease but should make you feel better.
· These side effects may occur: nausea, vomiting, loss of appetite, diarrhea; headache, dizziness.
· Avoid sexual intercourse while visible lesions are present.
· Report difficulty urinating, rash, increased severity or frequency of recurrences.
Topical administration
· Wear rubber gloves or finger cots when applying the drug to prevent autoinoculation of other sites and transmission to others.
· This drug does not cure the disease; application during symptom-free periods will not prevent recurrences.
· Avoid sexual intercourse while visible lesions are present.
· This drug may cause burning, stinging, itching, rash; notify your physician if these are pronounced.

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